A variable is a named location in memory to store data temporarily. PHP is dynamically typed language. So, there is no need for mentioning the data type of a variable. The type will be detected automatically based on the value assigned to the variable. A variable can be created as shown below:
$var1 = 10;
A variable which is not assigned a value contains NULL. In expressions containing numbers, NULL will be coerced to 0 and in case of strings, NULL will be coerced to an empty string. A variable can be printed as shown below:
print(“Value of var1 is: $var1”);
A variable can be checked if it contains a value other than NULL by using the function IsSet. This function returns TRUE if the variable contains a non-NULL value and FALSE if it contains a NULL value.
A video tutorial on declaring and using variables in PHP scripts: