What is hoisting in JavaScript?

Hoisting in JavaScript refers specifically to the behavior where variable and function declarations are moved to the top of their containing scope during the compilation phase. This means that you can use variables and functions before they are actually declared in the code.

In the context of variable declarations, when you declare a variable using var, let, or const, the declaration (but not the assignment) is hoisted to the top of the function or global scope. If you try to access a hoisted variable before its declaration in the code, it can lead to unexpected results—like getting undefined for var declarations or causing a ReferenceError for let and const declarations.

This feature of hoisting allows developers a level of flexibility in structuring their code, but it can also lead to confusion for those who are not aware of how JavaScript handles these declarations internally. Understanding hoisting is crucial for mastering variable scopes and lifetimes in JavaScript.

Other answer choices do not accurately represent the concept of hoisting. The idea of optimizing code performance, improving memory usage, or methods for declaring arrays does not align with the definition or implications of hoisting within the JavaScript execution context.