What are the rules for naming a PHP variable?

Naming a variable in PHP is simple, but some rules must be followed. Variable names must begin with a letter or an underscore, followed by any number of letters, numbers, or underscores. Additionally, PHP variable names are case sensitive, meaning that a variable named ‘myVariable’ is distinct from ‘my variable.’ Furthermore, variable names cannot use PHP keywords such as ‘int,’ ‘float,’ or ‘array.’