What does the 'this' keyword refer to in JavaScript?

In JavaScript, the 'this' keyword is a powerful feature that refers to the context in which a function is executed. This means that 'this' typically points to the object that is currently executing the function. When a method is called on an object, 'this' inside that method refers to the object itself. For instance, if you have an object with a method, within that method, 'this' will refer to the object containing the method when it is invoked.

In functions that are executed in the global context, 'this' will refer to the global object (like window in browsers). However, when functions are used in different contexts, such as within an event handler or when called directly, the value of 'this' can vary significantly, which can lead to confusion. In strict mode, 'this' can be undefined if a function is called without being associated with an object.

The notion that 'this' can change its reference based on execution context makes it crucial for developers to understand how function invocation affects the value of 'this'. Thus, the context of the current execution, usually an object, is the most accurate definition of 'this' in JavaScript.