What is a closure

A closure is a function that retains access to its lexical scope, even when the function is executed outside that scope. In other words, a closure allows a function to "remember" the environment in which it was created, capturing variables from its outer function.

Closures are commonly used to create private variables or to maintain a state in asynchronous programming.


        <?php
        function outerFunction($outerVariable) {
            return function($innerVariable) use ($outerVariable) {
                return $outerVariable + $innerVariable;
            };
        }

        $closure = outerFunction(5);
        echo $closure(10); // Outputs: 15
        ?>