Explain the prototype chain and its role in property lookup.
Objects can inherit properties and methods from their prototypes through a process called the prototype chain. The prototype chain is a series of linked objects that are used for property and method lookup. When you try to access a property on an object, JavaScript first checks if the property exists on the object itself. If not, it looks at the object's prototype a the object referenced by its [[Prototype]] property. This process continues up the chain until the property is found or until the chain reaches the global Object.prototype object, which is the ultimate ancestor of all objects.