Difference between "crawl" and "spider"

In terms of search engine optimization (SEO), there's a whole lot of difference between the terms "crawl" and "spider". They are familiar to us which crawl is where we sneak up and spider is an arachnid type of animal. But we're now in the internet world, and it's a whole lot of new meanings when using "crawl" and "spider" in web optimizing.

If you're talking about "crawling" your site, it means that your site indexed by Google and it appears in the search results, while "spider" means one site will allow links to be juiced up in the rankings by means of do-follow attribute. No-follow attributes don't allow links to juice up, but they still can get you more traffic.

This is where "crawl" and "spider" means in the world of web optimization.