What is the primary use of the 'async' keyword in JavaScript?

The primary use of the 'async' keyword in JavaScript is to declare a function that operates asynchronously. When you prefix a function with 'async', it allows the function to return a promise implicitly. This means that the function will execute asynchronously, enabling you to pause execution with 'await', which resolves promises in a more readable manner than traditional promise chaining. The 'async' keyword is especially useful in dealing with asynchronous operations like fetching data from APIs, allowing developers to write cleaner and more maintainable code without getting deep into callback hell.

In this context, 'async' transforms the way you write functions that engage in tasks that take time to complete, such as network requests, providing a simpler syntax to manage asynchronous behavior effectively.