Link popularity is the number of hyperlinks pointed to your website. It's also a lot of times used as term

Here's an example of how I consider link popularity works:

Let's say that Sally Pizza Palace Web site has a link to Michael Clothing store. This almost certainly won't assist Michael link popularity for the keywords "men's clothing." However, if both Sally Pizza Palace and Michael Men's Clothing Store are both situated in the city of Sydney, and people are penetrating for "men's clothing in Sydney," the excellence of that link, may have now gone up a small. There's now a ordinary thread (Sydney) between the sites. It probably won't help for those people simply probing for men's clothing, but may help if they're searching particularly for stores in the City of Sydney. A higher quality link for Michael, though, would be one from "Sam's Clothing Store Directory," which lists a whole group of clothing stores that can be found on the Internet. That is precisely the kind of link that the search engines would credit in the direction of link popularity. The key is in having that ordinary thread between the sites.