I’m flattered that you think I have a thorough understanding of SEO! It’s a moving target, really, because Google is changing its algorithms so often these days…
For the benefit of others who are reading this and are completely new to SEO, I’ll start from the beginning.
What is a “backlink”?
A backlink is clickable text that leads from one website to another website. The reason we call it a “back” link is that we’re trying to get other websites to link “back” to pages on our website(s)
There are two reasons why I try to get backlinks:
(1) To get traffic to one of my web pages. When people click on a backlink, they’re taken to the web page (my web page) that is specified in that link.
(2) To get additional PageRank for my web page. PageRank is an indicator that Google uses to determine the importance of a web page. When a lot of important web pages (i.e. web pages with high PageRank) link to my page, Google takes that as a vote of confidence, and assigns a high PageRank to my page, too.
(Contrary to popular belief, the word “Page” in PageRank doesn’t refer to a web page – it’s named after Larry Page, one of the two co-founders of Google.)
The way that PageRank is passed from one web page to another is through Google’s “crawlers” (also known as “bots”). A search engine crawler is a program that browses web pages and creates copies of the content on those pages. The crawler may also follow the links on those pages to other websites, depending on the TYPE of link.
There are two types of links: a “dofollow” link, and a “nofollow” link. Dofollow links contain code that tells the search engine crawler to follow that link to my web page. The crawler then “passes PageRank”, which means that my page will get a little boost in credibility or status, because another site is recommeding my page. When a link is “nofollow”, it tells the crawler to NOT follow the link to my web page.
Should I try to get only dofollow links to my web pages?
No, you should try to get both dofollow and nofollow links. There are a couple of reasons why you should try to get both types of links:
(1) While nofollow links don’t pass PageRank to your site, you’ll still get traffic from that link when people click on it.
(2) Perhaps more importantly, if you only have dofollow backlinks coming into your website, Google may see that as “unnatural”, and penalize your site (I don’t have proof that this happens, but my SEO manager believes it’s the case).
Neal, your questions have inspired me to write a longer blog post on SEO. Look for that on the blog soon.
Hope that helps, and let me know if you have other questions.