CSS Selectors are patterns used to select elements within an HTML document for styling or data extraction. In the context of web scraping, CSS selectors are employed to pinpoint specific HTML elements from which data needs to be extracted. They are used in conjunction with parsing libraries like Beautiful Soup and Scrapy to navigate and extract data efficiently. CSS selectors can target elements based on their tag names, classes, IDs, attributes, and hierarchical relationships, making them a powerful tool for accessing precise parts of a webpage. Mastery of CSS selectors is essential for effective web scraping, enabling precise and efficient data extraction from complex web structures.