Can you explain what is meant by the concept of variable lifting in programming?

In PHP, the concept of hoisting means that variable and function declarations are processed by the interpreter before executing the code. For functions, this means they can be called before their actual declaration in the code.

However, for variables in PHP, hoisting as in JavaScript does not occur: variables must be declared or assigned a value before use, otherwise they are undefined.

Example with a function:

sayHello(); // Works, function is hoisted

function sayHello() {
    echo "Hello!";
}

Example with a variable:

echo $a; // Will give a warning, variable not defined
$a = 5;

Thus, in PHP, hoisting applies only to functions, and variables need to be declared before use.