Spiders, Robots and Crawlers are all the same.
The search engine spiders, crawl throughout the web. The content they come across are indexed in their massive search indices. The webpages that are indexed, are grouped according to their authority, trust, high-quality content and the number of backlinks.
The job of these search spiders is to crawl the entire web 24 x 7.
Another term to take account of is, crawl rate. Crawl rate refers to the rate at which the search spiders crawl a particular site or blog.
