CoinMarketCap is a widely used website for tracking the capitalization and trading prices of various cryptocurrencies, offering detailed data like market cap, price, volume, circulating supply, and price changes over 24 hours. The CoinMarketCap API, accessible for free through RapidAPI, provides endpoints for retrieving lists of cryptocurrencies, specific cryptocurrency information, and global cryptocurrency data. To use the API, users must register for a free RapidAPI account, navigate to the CoinMarketCap API page, and select a preferred programming language such as NodeJS, PHP, Python, Ruby, Objective-C, Java, C#, or cURL to test endpoints. The tutorial provides detailed instructions and code snippets for integrating the API into applications, facilitating easy access to comprehensive cryptocurrency data for developers.