# Extension - `v::extension(string $extension)` Validates if the file extension matches the expected one: ```php v::extension('png')->validate('image.png'); // true ``` This rule is case-sensitive. *** See also: * [Directory](Directory.md) * [Executable](Executable.md) * [Exists](Exists.md) * [File](File.md) * [Image](Image.md) * [Mimetype](Mimetype.md) * [Readable](Readable.md) * [Size](Size.md) * [SymbolicLink](SymbolicLink.md) * [Uploaded](Uploaded.md) * [Writable](Writable.md)