Scrapy's CrawlSpider is a generic spider class designed specifically for crawling entire websites. Unlike regular Spiders, CrawlSpider provides a rules system that can automatically follow links and extract data. CrawlSpider uses LinkExtractor to extract links from pages and Rule to define how to handle these links. Rules can specify callback functions, whether to follow links, link extractors, etc. CrawlSpider is particularly suitable for crawling structured websites such as news sites, e-commerce sites, etc. Using CrawlSpider can reduce the workload of writing repetitive code and improve development efficiency. It's important to note that CrawlSpider's parse method is already used by the rules system, and developers should not override it but define other callback functions. CrawlSpider also supports depth control, domain restrictions, and other features to precisely control the crawling scope.