Concept of variables in php

- First character must be start with $

- Second character should be start with either alphabet or underscore like ($_ , $a etc)

- Space are not allowed.If you try to use space in variables name then PHP will throw parse error like below:

Parse error: syntax error, unexpected 'b' (T_STRING)

- Special characters are not allowed except _ .So if you try to put special characters in php variables name then it always throw  Parse error.

- You can use numbers after second character.Example ( $_123,$a123,@a_b123) these are the correct variable name.

Examples :

Correct : $_a, $a_fsdf , $_123, $a1nb etc

Wrong :  account, $1asd ,$aaa$df, $test abc etc