The variable is temporary area which hold the information.
Example for for PHP Variable
echo “Number :$n and $m”;
Naming Rules/Convention for Variables
• PHP variable name only start with a letter or an underscore “_”
• PHP variable name can only contain alpha-numeric characters and underscores (a-z, A-Z, 0-9, and _ )
• PHP variable name should not contain spaces. For more than one word should be separated by underscore ($w3_html), or with capitalization ($w3Html)
• PHP variable $n and $N both are different .In PHP variable name is case sensitive