QUOTE(msherry @ Nov 21 2012, 09:44 AM)
A spider also called crawler is a piece of software that follows links throughout the Internet, grabbing content from sites and adding it to search engine databases.
Spider, crawler and indexer these are co-related terms to each other. A spider is a program, which is designed like to follow all the links or go through with all the links in a pattern after that adding it to the huge search engine database. Please tell me something more about "grabbing content"