In PHP, a variable is a container that stores a value or a reference to a value. A variable is represented by a dollar sign ($) followed by the variable name. Variable names are case-sensitive.
Here are some examples of declaring variables in PHP:
<?php
$name = "John";
$age = 30;
$salary = 45000.50;
$is_employed = true;
$colors = array("red", "green", "blue");
$person = new stdClass();
?>
In the above example, $name is a string variable that stores the value “John”, $age is an integer variable that stores the value 30, $salary is a floating-point variable that stores the value 45000.50, $is_employed is a Boolean variable that stores the value true, $colors is an array variable that stores the values “red”, “green”, and “blue”, and $person is an object variable that stores a new instance of the stdClass object.
You can use variables in PHP just like you would in any other programming language. For example, you can perform arithmetic operations on numeric variables, concatenate strings, and access array elements using their keys.
<?php
$x = 10;
$y = 5;
$sum = $x + $y;
$difference = $x - $y;
$product = $x * $y;
$quotient = $x / $y;
$remainder = $x % $y;
$greeting = "Hello, ";
$name = "John";
$message = $greeting . $name;
$colors = array("red", "green", "blue");
echo $colors[0]; // "red"
?>