diff --git a/.idea/misc.xml b/.idea/misc.xml
index 705eb91..fcd6147 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -3,10 +3,15 @@
   <component name="DesignSurface">
     <option name="filePathToZoomLevelMap">
       <map>
+        <entry key="app/src/main/res/drawable/received_border.xml" value="0.332" />
+        <entry key="app/src/main/res/layout/activity_chat.xml" value="0.4375" />
         <entry key="app/src/main/res/layout/activity_log_in.xml" value="0.4375" />
         <entry key="app/src/main/res/layout/activity_login.xml" value="0.37083333333333335" />
         <entry key="app/src/main/res/layout/activity_main.xml" value="0.35625" />
         <entry key="app/src/main/res/layout/activity_sign_up.xml" value="0.4375" />
+        <entry key="app/src/main/res/layout/receive.xml" value="0.3098958333333333" />
+        <entry key="app/src/main/res/layout/received.xml" value="0.4375" />
+        <entry key="app/src/main/res/layout/sent.xml" value="0.43645833333333334" />
         <entry key="app/src/main/res/layout/user_layout.xml" value="0.25" />
         <entry key="app/src/main/res/menu/main_menu.xml" value="0.4375" />
       </map>
diff --git a/app/build.gradle b/app/build.gradle
index f098d63..48e2221 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -48,4 +48,5 @@ dependencies {
     androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
     implementation platform('com.google.firebase:firebase-bom:31.0.1')
     implementation 'com.google.firebase:firebase-analytics-ktx'
+    implementation 'com.google.android.gms:play-services-ads:21.3.0'
 }
\ No newline at end of file
diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index 6327779..89553b7 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -2,7 +2,7 @@
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     package="com.lsm.chatapplication">
-
+    <uses-permission android:name="android.permission.INTERNET"/>
     <application
         android:allowBackup="true"
         android:dataExtractionRules="@xml/data_extraction_rules"
@@ -15,7 +15,8 @@
         tools:targetApi="31">
         <activity
             android:name=".ChatActivity"
-            android:exported="false" />
+            android:exported="false"
+            android:parentActivityName=".MainActivity"/>
         <activity
             android:name=".SignUp"
             android:exported="false"
@@ -32,6 +33,12 @@
         <activity
             android:name=".MainActivity"
             android:exported="false" />
+        <!-- Sample AdMob app ID: ca-app-pub-3940256099942544~3347511713 -->
+        <meta-data
+            android:name="com.google.android.gms.ads.APPLICATION_ID"
+            android:value="ca-app-pub-3940256099942544~3347511713"/>
+
     </application>
 
+
 </manifest>
\ No newline at end of file
diff --git a/app/src/main/java/com/lsm/chatapplication/ChatActivity.kt b/app/src/main/java/com/lsm/chatapplication/ChatActivity.kt
index ad902b2..092b2e8 100644
--- a/app/src/main/java/com/lsm/chatapplication/ChatActivity.kt
+++ b/app/src/main/java/com/lsm/chatapplication/ChatActivity.kt
@@ -1,11 +1,81 @@
 package com.lsm.chatapplication
 
+import android.content.Intent
 import androidx.appcompat.app.AppCompatActivity
 import android.os.Bundle
+import android.widget.LinearLayout
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
+import com.google.firebase.auth.FirebaseAuth
+import com.google.firebase.database.DataSnapshot
+import com.google.firebase.database.DatabaseError
+import com.google.firebase.database.DatabaseReference
+import com.google.firebase.database.ValueEventListener
+import com.google.firebase.database.ktx.database
+import com.google.firebase.ktx.Firebase
+import com.lsm.chatapplication.databinding.ActivityChatBinding
 
 class ChatActivity : AppCompatActivity() {
+    private lateinit var binding: ActivityChatBinding
+    private lateinit var messageAdapter: MessageAdapter
+    private lateinit var messageList: ArrayList<Message>
+    private lateinit var mDbRef: DatabaseReference
+
+    private var receiverRoom: String? = null
+    private var senderRoom: String? = null
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
-        setContentView(R.layout.activity_chat)
+        binding = ActivityChatBinding.inflate(layoutInflater)
+        setContentView(binding.root)
+
+        val name = intent.getStringExtra("name")
+        val receiverUid = intent.getStringExtra("uid")
+        val senderUid = FirebaseAuth.getInstance().currentUser?.uid
+        mDbRef = Firebase.database("https://chatapplication-4eb49-default-rtdb.europe-west1.firebasedatabase.app/").reference
+
+        senderRoom = receiverUid + senderUid
+        receiverRoom = senderUid + receiverUid
+
+        supportActionBar?.title = name
+
+        messageList = ArrayList()
+        messageAdapter = MessageAdapter(messageList)
+
+        binding.messagesRecyclerView.layoutManager = LinearLayoutManager(this)
+        binding.messagesRecyclerView.adapter = messageAdapter
+
+        mDbRef.child("chats").child(senderRoom!!).child("messages").
+            addValueEventListener(object: ValueEventListener{
+                override fun onDataChange(snapshot: DataSnapshot) {
+
+                    messageList.clear()
+
+                    snapshot.children.forEach{
+                        val message = it.getValue(Message::class.java)
+                        messageList.add(message!!)
+                    }
+                    messageAdapter.notifyItemInserted(messageList.size-1)
+                }
+
+                override fun onCancelled(error: DatabaseError) {
+                    TODO("Not yet implemented")
+                }
+
+            })
+
+        binding.sendMessageButton.setOnClickListener{
+            val message = binding.messageBox.text.toString()
+            if (message != ""){
+                val messageObject = Message(message,senderUid)
+
+                mDbRef.child("chats").child(senderRoom!!).child("messages").push()
+                    .setValue(messageObject).addOnSuccessListener {
+                        mDbRef.child("chats").child(receiverRoom!!).child("messages").push()
+                            .setValue(messageObject)
+                    }
+                binding.messageBox.text.clear()
+
+            }
+        }
     }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/lsm/chatapplication/LogIn.kt b/app/src/main/java/com/lsm/chatapplication/LogIn.kt
index 91fd34c..0b4bae5 100644
--- a/app/src/main/java/com/lsm/chatapplication/LogIn.kt
+++ b/app/src/main/java/com/lsm/chatapplication/LogIn.kt
@@ -34,6 +34,10 @@ class LogIn : AppCompatActivity() {
         }
     }
     private fun logIn(email: String, password: String){
+        if(email.isEmpty() or password.isEmpty()){
+            Toast.makeText(this@LogIn,"Field cannot be empty",Toast.LENGTH_SHORT).show()
+            return
+        }
         mAuth.signInWithEmailAndPassword(email, password)
             .addOnCompleteListener(this) { task ->
                 if (task.isSuccessful) {
diff --git a/app/src/main/java/com/lsm/chatapplication/MainActivity.kt b/app/src/main/java/com/lsm/chatapplication/MainActivity.kt
index 0ff0973..a192ab0 100644
--- a/app/src/main/java/com/lsm/chatapplication/MainActivity.kt
+++ b/app/src/main/java/com/lsm/chatapplication/MainActivity.kt
@@ -6,6 +6,10 @@ import android.os.Bundle
 import android.view.Menu
 import android.view.MenuItem
 import androidx.recyclerview.widget.LinearLayoutManager
+import com.google.android.gms.ads.AdRequest
+import com.google.android.gms.ads.AdView
+import com.google.android.gms.ads.MobileAds
+import com.google.android.gms.ads.initialization.OnInitializationCompleteListener
 import com.google.firebase.auth.FirebaseAuth
 import com.google.firebase.database.DataSnapshot
 import com.google.firebase.database.DatabaseError
@@ -35,6 +39,8 @@ class MainActivity : AppCompatActivity() {
         binding.userRecyclerView.adapter = adapter
 
         readUsersFromDatabase()
+        val adRequest = AdRequest.Builder().build()
+        binding.adView.loadAd(adRequest)
     }
 
     private fun readUsersFromDatabase(){
diff --git a/app/src/main/java/com/lsm/chatapplication/Message.kt b/app/src/main/java/com/lsm/chatapplication/Message.kt
new file mode 100644
index 0000000..983e5a7
--- /dev/null
+++ b/app/src/main/java/com/lsm/chatapplication/Message.kt
@@ -0,0 +1,5 @@
+package com.lsm.chatapplication
+
+class Message(val message: String?, val senderId: String?) {
+    constructor(): this(null, null)
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/lsm/chatapplication/MessageAdapter.kt b/app/src/main/java/com/lsm/chatapplication/MessageAdapter.kt
new file mode 100644
index 0000000..ff55a2b
--- /dev/null
+++ b/app/src/main/java/com/lsm/chatapplication/MessageAdapter.kt
@@ -0,0 +1,63 @@
+package com.lsm.chatapplication
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import androidx.recyclerview.widget.RecyclerView
+import com.google.firebase.auth.FirebaseAuth
+import com.lsm.chatapplication.databinding.ReceivedBinding
+import com.lsm.chatapplication.databinding.SentBinding
+import com.lsm.chatapplication.databinding.UserLayoutBinding
+
+class MessageAdapter(val messageList: ArrayList<Message>): RecyclerView.Adapter<RecyclerView.ViewHolder>() {
+
+    private val ITEM_RECEIVED = 0
+    private val ITEM_SENT = 1
+
+    class SentViewHolder(val binding: SentBinding): RecyclerView.ViewHolder(binding.root)
+    class ReceivedViewHolder(val binding: ReceivedBinding): RecyclerView.ViewHolder(binding.root)
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+        return if(viewType == ITEM_RECEIVED){
+            ReceivedViewHolder(
+                ReceivedBinding.inflate(
+                    LayoutInflater.from(parent.context),
+                    parent,
+                    false
+                )
+            )
+        }else{
+            SentViewHolder(
+                SentBinding.inflate(
+                    LayoutInflater.from(parent.context),
+                    parent,
+                    false
+                )
+            )
+        }
+    }
+
+    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
+        val currentMessage = messageList[position]
+        if(holder.javaClass == SentViewHolder::class.java){
+            val viewHolder = holder as SentViewHolder
+            holder.binding.txtSentMessage.text = currentMessage.message
+        }else{
+            val viewHolder = holder as ReceivedViewHolder
+            holder.binding.txtReceivedMessage.text = currentMessage.message
+        }
+    }
+
+    override fun getItemCount(): Int {
+        return messageList.size
+    }
+
+    override fun getItemViewType(position: Int): Int {
+        val currentMessage = messageList[position]
+
+        return if(FirebaseAuth.getInstance().currentUser?.uid.equals(currentMessage.senderId)){
+            ITEM_SENT
+        }else{
+            ITEM_RECEIVED
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/com/lsm/chatapplication/SignUp.kt b/app/src/main/java/com/lsm/chatapplication/SignUp.kt
index 7b90991..f4944f3 100644
--- a/app/src/main/java/com/lsm/chatapplication/SignUp.kt
+++ b/app/src/main/java/com/lsm/chatapplication/SignUp.kt
@@ -35,6 +35,10 @@ class SignUp : AppCompatActivity() {
         }
     }
     private fun signUp(name:String, email: String, password: String){
+        if(email.isEmpty() or password.isEmpty() or name.isEmpty()){
+            Toast.makeText(this@SignUp,"Field cannot be empty",Toast.LENGTH_SHORT).show()
+            return
+        }
         mAuth.createUserWithEmailAndPassword(email, password)
             .addOnCompleteListener(this) { task ->
                 if (task.isSuccessful) {
diff --git a/app/src/main/java/com/lsm/chatapplication/UserAdapter.kt b/app/src/main/java/com/lsm/chatapplication/UserAdapter.kt
index c3475ad..0b5d4aa 100644
--- a/app/src/main/java/com/lsm/chatapplication/UserAdapter.kt
+++ b/app/src/main/java/com/lsm/chatapplication/UserAdapter.kt
@@ -1,11 +1,13 @@
 package com.lsm.chatapplication
 
+import android.content.Intent
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import androidx.recyclerview.widget.DiffUtil
 import androidx.recyclerview.widget.ListAdapter
 import androidx.recyclerview.widget.RecyclerView
+import com.google.firebase.auth.FirebaseAuth
 import com.lsm.chatapplication.databinding.UserLayoutBinding
 
 //class UserAdapter(val userList: ArrayList<User>):
@@ -20,6 +22,7 @@ import com.lsm.chatapplication.databinding.UserLayoutBinding
 //    override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
 //        val currentUser = userList[position]
 //        holder.binding.userName.text = currentUser.name
+//        holder.binding.itemView
 //    }
 //
 //    override fun getItemCount(): Int {
@@ -47,7 +50,16 @@ class UserAdapter():
 
     override fun onBindViewHolder(holder: UserViewHolder, position: Int) {
         val currentUser = getItem(position)
+        //?
+        val context = holder.binding.root.context
         holder.binding.userName.text = currentUser.name
-    }
+        holder.itemView.setOnClickListener{
+            val intent = Intent(context,ChatActivity::class.java)
 
+            intent.putExtra("name",currentUser.name)
+            intent.putExtra("uid", currentUser.uid)
+
+            context.startActivity(intent)
+        }
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/res/drawable/ic_send_blue.xml b/app/src/main/res/drawable/ic_send_blue.xml
new file mode 100644
index 0000000..d1a4c46
--- /dev/null
+++ b/app/src/main/res/drawable/ic_send_blue.xml
@@ -0,0 +1,5 @@
+<vector android:autoMirrored="true" android:height="48dp"
+    android:tint="#3700B3" android:viewportHeight="24"
+    android:viewportWidth="24" android:width="48dp" xmlns:android="http://schemas.android.com/apk/res/android">
+    <path android:fillColor="@android:color/white" android:pathData="M2.01,21L23,12 2.01,3 2,10l15,2 -15,2z"/>
+</vector>
diff --git a/app/src/main/res/drawable/received_border.xml b/app/src/main/res/drawable/received_border.xml
new file mode 100644
index 0000000..07372d9
--- /dev/null
+++ b/app/src/main/res/drawable/received_border.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="utf-8"?>
+<shape xmlns:android="http://schemas.android.com/apk/res/android">
+    <corners android:radius="15dp"/>
+    <stroke android:color="@color/purple_700" android:width="3dp"/>
+</shape>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_chat.xml b/app/src/main/res/layout/activity_chat.xml
index 99d07ff..4d9424c 100644
--- a/app/src/main/res/layout/activity_chat.xml
+++ b/app/src/main/res/layout/activity_chat.xml
@@ -6,4 +6,39 @@
     android:layout_height="match_parent"
     tools:context=".ChatActivity">
 
+    <androidx.recyclerview.widget.RecyclerView
+        android:id="@+id/messages_recycler_view"
+        android:layout_width="match_parent"
+        android:layout_height="0dp"
+        android:layout_marginBottom="16dp"
+        app:layout_constraintBottom_toTopOf="@+id/send_message_button"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent">
+
+    </androidx.recyclerview.widget.RecyclerView>
+
+    <EditText
+        android:id="@+id/message_box"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="16dp"
+        android:layout_marginEnd="16dp"
+        android:ems="10"
+        android:hint="@string/message_box_hint"
+        android:inputType="textPersonName"
+        app:layout_constraintBottom_toBottomOf="@+id/send_message_button"
+        app:layout_constraintEnd_toStartOf="@+id/send_message_button"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="@+id/send_message_button" />
+
+    <ImageView
+        android:id="@+id/send_message_button"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginEnd="16dp"
+        android:layout_marginBottom="16dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:srcCompat="@drawable/ic_send_blue" />
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/activity_log_in.xml b/app/src/main/res/layout/activity_log_in.xml
index 4de4080..3dd367e 100644
--- a/app/src/main/res/layout/activity_log_in.xml
+++ b/app/src/main/res/layout/activity_log_in.xml
@@ -29,6 +29,7 @@
         android:ems="10"
         android:hint="@string/email_hint"
         android:inputType="textEmailAddress"
+        android:minHeight="48dp"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintTop_toBottomOf="@+id/app_logo" />
@@ -41,6 +42,7 @@
         android:ems="10"
         android:hint="@string/password_hint"
         android:inputType="textPassword"
+        android:minHeight="48dp"
         app:layout_constraintEnd_toEndOf="@+id/edt_email"
         app:layout_constraintHorizontal_bias="1.0"
         app:layout_constraintStart_toStartOf="@+id/edt_email"
diff --git a/app/src/main/res/layout/activity_main.xml b/app/src/main/res/layout/activity_main.xml
index ae9993c..1e2be4c 100644
--- a/app/src/main/res/layout/activity_main.xml
+++ b/app/src/main/res/layout/activity_main.xml
@@ -9,10 +9,23 @@
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/user_recycler_view"
         android:layout_width="match_parent"
-        android:layout_height="match_parent"
-        tools:listitem="@layout/user_layout"
+        android:layout_height="wrap_content"
+        app:layout_constraintBottom_toTopOf="@+id/ad_view"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintVertical_bias="0.0"
+        tools:listitem="@layout/user_layout" />
+
+    <com.google.android.gms.ads.AdView
+        android:id="@+id/ad_view"
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        app:adSize="BANNER"
+        app:adUnitId="ca-app-pub-3940256099942544/6300978111"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintStart_toStartOf="parent" />
+
 </androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/received.xml b/app/src/main/res/layout/received.xml
new file mode 100644
index 0000000..6763a57
--- /dev/null
+++ b/app/src/main/res/layout/received.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
+
+    <com.google.android.material.card.MaterialCardView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="32dp"
+        android:layout_marginTop="16dp"
+        app:cardCornerRadius="15dp"
+        app:cardElevation="4dp"
+        app:contentPadding="8dp"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="0.0"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:strokeColor="@color/purple_700"
+        app:strokeWidth="3dp">
+
+        <TextView
+            android:id="@+id/txt_received_message"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="This is received message"
+            android:textSize="18sp" />
+    </com.google.android.material.card.MaterialCardView>
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/layout/sent.xml b/app/src/main/res/layout/sent.xml
new file mode 100644
index 0000000..a010f85
--- /dev/null
+++ b/app/src/main/res/layout/sent.xml
@@ -0,0 +1,30 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content">
+
+    <com.google.android.material.card.MaterialCardView
+        android:layout_width="wrap_content"
+        android:layout_height="wrap_content"
+        android:layout_marginTop="16dp"
+        android:layout_marginEnd="32dp"
+        app:cardBackgroundColor="@color/purple_700"
+        app:cardCornerRadius="15dp"
+        app:cardElevation="4dp"
+        app:contentPadding="8dp"
+        app:layout_constraintBottom_toBottomOf="parent"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintHorizontal_bias="1.0"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toTopOf="parent">
+
+        <TextView
+            android:id="@+id/txt_sent_message"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:text="This is sent message"
+            android:textColor="@color/white"
+            android:textSize="18sp" />
+    </com.google.android.material.card.MaterialCardView>
+</androidx.constraintlayout.widget.ConstraintLayout>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 3ad994b..9bd0035 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -1,5 +1,5 @@
 <resources>
-    <string name="app_name">ChatApplication</string>
+    <string name="app_name">Chat Application</string>
     <string name="email_hint">Email</string>
     <string name="password_hint">Password</string>
     <string name="log_in_btn_text">Log In</string>
@@ -7,4 +7,5 @@
     <string name="sign_up_btn_text">Create new account</string>
     <string name="options_separator_text">Or</string>
     <string name="logout_menu">Log Out</string>
+    <string name="message_box_hint">Type a message</string>
 </resources>
\ No newline at end of file