What is an Immediately Invoked Function Expression (IIFE)?

An Immediately Invoked Function Expression, commonly known as an IIFE, is defined as a function that is executed immediately after it is created. This means that as soon as the function's declaration is complete, it is called right away without the need for any additional function calls.

IIFEs are typically structured by enclosing the function definition within parentheses and then following it with another pair of parentheses to invoke it. This practice is notably useful for creating a new local scope to avoid polluting the global namespace, particularly when dealing with variables and avoiding conflicts in larger applications.

The other choices do not capture the essence of an IIFE accurately. A function that runs when called by another function refers to a different concept altogether, and a function that runs after a delay describes setTimeout behavior, while a function that accepts multiple inputs refers to handling arguments within a function, which is unrelated to the IIFE concept.