Article marketing should be writing and submitting articles to drive traffic to your site eventually gain a backlink to your site. Article marketing is one of the most popular ways to build backlinks and every single article that gets posted counts as a backlink.
Spider or Crawler:
Search engine spider so called, crawler or bot or robot is nothing but a software is especially made for in such a way to wandering every website copy the html part i.e., the text part and past it to the search engine server. Their job is to just crawl new sites, changing of the existing site, and indexes the downloaded pages so that users can search them much more quickly.