Forgive my complete noob-ness, but I'm new to SEO and I see a lot of talk about "dofollow" and "nofollow." What are these things, and what can they do if I want to market a blog I have? Thanks for any responses.
Dofollow means, Google can crawl and the link and it gets credit towards indexing and pagerank. Nofollow means, rel="nofollow" tag added on each link, usually on commentators URL by default on blogspot or wordpress blogs that don't give any credit towards pagerank or ranking in google as google don't give credit to rel="nofollow" tag added. Usually, Google's advice to add nofollow tag on paid links. For new blogs, removing rel="nofollow" tag on commentators link (dofollow blog) helps to get many comments on each blog post and traffic will increase too. But, this is another way to welcome spam comments. Usually, bloggers who able to establish or unable to control spam comments will add back nofollow tag to make their blog "nofollow blog". There are several ways to detect dofollow and nofollow blogs. Just check commentators link on any post whether it is rel="nofollow" tag added or not. If it is added, than it is nofollow blog. If you can't find nofollow tag, than it is dofollow. You can also use some tools to help you verify dofollow and nofollow links.
"Dofollow" is a link in its natural state, whereas "nofollow" is a value added to the rel="" attribute in the anchor element that tells the search engines not to follow the link to its destination. Here are some examples: <a href="http://www.example.com">Example Link</a> <a href="http://www.example.com" rel="nofollow">This is not the link you are looking for.</a> Code (markup):
Google and other search engines using 'links' as votes in their algorithms realized that people can easily buy a lot of links and can 'game' their system. So they proposed an attribute rel=nofollow to be used for paid links. The initial usage was for blog / forum / guestbook links (again a lot of spamming was happening there).