With web today you "sorta haveta" have a rank in major search engines if you want to be seen. I mean with 250,000,000, yes 250 million searches a day on Google™ alone, how are your visitors and potential customers going to find you?
Now, there are numerous ways in which a Search Engine ranks a website; by keyword density, relevancy, content, etc. etc.. But Link Popularity is an ever growing statistic in how Search Engines continue to rank websites.
Link popularity, is how "popular" your website is. That is how popular your site is compared to other websites. To put it another way; it is number of "other websites" that have a link on their website to your website. Did you get that? :)
Now, although Link Popularity "building" is a large science and art in itself, I'll briefly touch on a couple ways in which you can see how popular you are and how to go about improving your link popularity.
A small side note though, is link popularity is a BIG way in which Google™ ranks their search results. They refer to this as "PageRank". With Search Engine, FAST, they it call "link score".
Now there are quite a few software programs and sites that can help build your link popularity as well as check your popularity.
Now, there are many ways to check your link popularity. But if you simply want to get a small idea, a little way for you to do this is go to any search engine and type in, "link popularity", without quotes, and there will be lots of results for you to choose from. And then simply pick a site and check your site popularity.