What is a search engine spider?

A spider is the robot program used by a search engine to index the World Wide Web content. A spider captures specific information about a page. Some capture the title and the first so many characters of content, some capture the title and meta tags, some capture specific inbound link information, some look for keywords in specific places and some use a combination of all of these methods.

These, also known as bots, crawl the internet and store information about websites. Search engine spiders follow links to find websites on the internet. Bots rely on both internal and external links for information acquisition.

A spider, also known as a robot or a crawler, is actually just a program that follows, or "crawls", links throughout the Internet, grabbing content from sites and adding it to search engine indexes.

Well yes crawlers, crawl the internet and store details about sites. Spiders follow hyper-links to find sites on the internet. Bots rely on both internal and external hyper-links for details acquisition. So if your site is properly Done with On page seo. The spiders would be pleased and prefer your site in search engines.