freeCodeCamp/guide/english/php/variable-basics/index.md

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PHP Variable Basics

Variables allow programmers to use data throuhgout a PHP script.

In PHP, variables always start with a $ symbol followed by the name of the variable. Only letters, numbers (may not be the first character), and underscores can make up the name of a variable.

For example, $my_variable, $anotherVariable, and $the2ndVariable are allow valid variable names.

Variable names are case-sensitive. $my_variable is different from $My_Variable which is different from $mY_vARiAblE.

Before a variable can be used, it must have a value assigned to it.

    <?php
    $my_number = 1;
    echo($my_number);
    
    >>> 1

In the example above, the variable is $my_number. The value assigned to it was the number 1. The variable was then passed as a parameter to the echo function, which output the value to the command line.