In Angular, a resolver is a mechanism that prepares the necessary data for a page while it is being loaded. When you're directed to a route, the resolver fetches predetermined data in advance, allowing you to quickly view the page without waiting for its complete loading. Resolvers are often used to perform asynchronous tasks like API calls, ensuring that the required data is readily available when the page loads, resulting in an enhanced user experience. Resolvers are defined in route configurations and execute data retrieval processes before accessing the route. As a result, the required data is instantly available when the page is loaded.