The simple difference is that dofollow links means u also have to link their website to ur site and nofollow means u don't have to link their site from where u got ur backlink.
Difference between dofollow and nofollow is that google crawl only dofollow site and google not crawl nofollow site, it is the difference between doffollow and nofollow.
If you are optimizing your website for search engines you have to do more then on-site optimization. For good search engine ranking you will need to get as many links pointing to your website as possible. While some links have high value many others are worthless. In this article you will learn the difference. Webmasters are aware of the fact that link building is the most important part of the SEO process. For this reason some of them started to post unrelated advertisements to weblogs and forums. These advertisements usually contain one or more links to their websites. This way they are trying to get higher pagerank and better ranking in search engines. This is one of the dirtiest black hat tactics around and people doing that are known as spammers. To minimize this sort of spam google developed nofollow attribute. Links with this attribute are called nofollow and links without it dofollow. Webmasters can use the nofollow attribute to decrease the value of the links on their websites. In fact the nofollow links have no value for more than 90% of search engines. So if you are going to gain new backlinks you should always check out if you will get dofollow link. There are 2 ways how to find out if the link is dofollow or nofollow: 1. Check the page source. Load the site in your browser and click right mouse button. From the menu select the option "View page source". The source will be opened in notepad or similar text editor. Then press CTRL + F, fill in the word "nofollow" to the search box and press ENTER to search for the nofollow attribute. This way you can find out which links on the website are nofollow. 2. Use firefox add-ons like Status search. These tools can be installed in your firefox browser and when enabled they will show you which links on the page are nofollow. How are nofollow links used by site owners? Using nofollow attribute is very popular in the bloggers community. On the other hand many weblog owners understand that quality comments mean additional value for their blogs. Search engines love fresh and often updated content and comments are one of the ways how to build it. At this point the weblog owners think how to attract more people to post their comments. And some of them will turn of the nofollow attribute because they understand that the visitors want some benefit for their commenting. So if you comment nofollow blog it is possible that links from it will be changed to dofollow in the future. Forum owners use another strategies. Most of them allow dofollow links in your signature and add nofollow attribute to the links in the post body. Other require that you have to be member of the forum at least some number of days and/or have made some number of quality posts. When you achieve this goal your links will be dofollow. You should be also careful when submitting links to the directories. Some of them require payment or at least link back for dofollow link. So always read the conditions on the submission page. Remember that you need to build only dofollow links because nofollow links are ignored by google. With this in mind your search engine optimization will be more effective.
I am sure, if you try to find by yourself in the search option given in the top right hand corner of this forum, you will find thousands of threads for the same. Anyways, my advice do not try to get entangled in the type of links you have, instead try to increase the number of backlinks for your site, doesnot matter if its do-follow or no-follow.
Do Follow links are links that are and that can be crawled by search engines. No-Follow links are, of course links that won’t be crawled by search engines. Google and other search engines likes right use for No-Follow attributed links. If you have web site and it links to already popular one, search engine “see†that, and might low your and site you linked to rankings.
Its very simple dofollow means follow that link and nofollow means not to follow that link. that attribute tells the search engine that follow or no follow that link.