keyword in URL, Link popularity

keyword in URL
Having keyword in your domain name and / or folder names and file names increases your chances to gain top positions for these keywords. If you aren't a brand-oriented business, it is recommended that you purchase the domain name that contains your keyword. If your keyphrase consists of more than one keyword, the best way to separate them in the URL is with a hyphen "-":
www.my-keyphrase-here.com
If it seems impossible to get such a domain name, or your site is already well established over a keyword-poor domain, attempt to compensate it by using keywords in folder and file names of your site's file system on the server.

Link popularity
This is the number of links from other website pages to your page that search engines are aware of.
Each search engine only lists links embedded on the sites that are preindexed by that particular search engine. So, the presence of certain links in Google's index will not guarantee that Inktomi has also indexed the same sites. Therefore the number of links shown will be different from engine to engine.

In general, the more links that point to your page, the better your page will rank.

However, a large number of links is not the deciding factor that helps your site get to the top of the results pages -- the quality of those links is of greater importance. If a link to your site is placed on a page having very little importance that is this page itself is linked to only a few other pages or none, this kind of link will not improve a page's popularity. The links to your pages should be subject-relevant because theme-based search engines will check the parity of content between referring and referred pages. The closer they are, the more relevant your site page is to the searcher's query for your keyword. Avoid reciprocal linking with sites that have a low weight, or a questionable reputation or are different from yours in subject matter. As a part of their anti-spam measures, search engines can penalize your site's rankings for ignoring these pitfalls.