Callbacks and Higher-Order Functions

setTimeout(function() {
  console.log('Hello, world!');
}, 1000);

It causes a syntax error
The function executes immediately
The function is executed when the outer function (setTimeout) calls it
When you pass an anonymous function as a callback, it works exactly the same as a named function. In this example, the anonymous function will be called after the 1000ms timeout completes. Anonymous functions are commonly used as callbacks when the function doesn't need to be reused elsewhere in the code. They provide a clean, concise way to define function behavior inline where it's needed.
Nothing happens because anonymous functions can't be callbacks