What are arrow functions and how do they differ from regular functions?

Arrow functions (const fn = (x) => x * 2;) are concise function expressions with key differences:

1. Lexical this: Arrow functions do not have their own this — they inherit this from the enclosing lexical scope. This is the most important difference. Regular functions bind this dynamically based on how they are called (call-site).
2. No arguments object: Arrow functions do not have an arguments object — use rest parameters (...args) instead.
3. Cannot be used as constructors: Cannot use new with an arrow function.
4. No prototype property. Lexical this makes arrow functions ideal for callbacks in class methods and event handlers where you want to preserve the class instance's this.