A variable is identified by the $ sign, which is followed by the variable's name.
The name of a variable must begin with a letter or an underscore.
A number cannot be the first character in a variable name.
Only alpha-numeric characters and underscores (A-z, 0-9, and _) are allowed in variable names.
PHP has three different variable scopes, depending on the scopes: local, global, and static variable scope.
A variable's value is the result of its most recent assignment. Variables in PHP don't have inherent types, which means they don't know if they'll be used to store a number or a string of characters before they're used. Variables with default values are those that are utilised before they are assigned.
Variables are used to store values or data in a programme so that they can be utilised later. Character values, numeric values, memory addresses, and strings are all stored in variables, which are similar to containers.