---
title: PHP Variables
---

### PHP - Vaiables Types

Varibles are the main way to store information in the middle way of a PHP program.
All variables in PHP are donated with a leading dollar sign like `$variable_name`.
Variables are assigned with the `= operator` , with the variable on the left-hand side and the expression to be evaluated on the right.

### Variable Naming

Rules for naming a variable is listed below:
 1. Variables names must begin with a letter or underscores character.
 2. A variable name can consist of numbers, letters, underscores but you cannot use characters like `+ , - , % , ( , ) . &` in its name.
 3. Variable names are case-sensitive i.e. `($age and $AGE are two different variables)`.

### Creating (Declaring) PHP Variables

In PHP, a variable starts with the $ sign, followed by the name of the variable. The code snippet given below shows it.

``` shell
 <?php
    $txt = "Hello world!";
    $x = 6;
    $y = 10.5;
 ?>
 ```
 
Variable lifecycle: In PHP variables have a default value. If a variable is not declared before you attempt to use it, its value will be NULL. It is unset. So you can't use it by writing `isset($variable)` before using it.