UPDATE: After the Google panda effect only useless links like comment links should be tagged as nofollow. Links pointing to your post pages should be kept dofollow like labels and archives
You waste an important use of your homepage PR when you don’t link your internal pages or when you link internal pages as nofollow. A PR flows like a river between all pages that you link to. The better the PR flow within your blog the better will your blog get indexed. Robots enjoy crawling content which is well organized in terms of linking. I have already discussed in detail on how to flow the PR juice to internal pages and just today I also published a post discussing the importance of nofollow tags. I shared in detail some steps that can help you better maintain your PR and make good use of it. It is really important that you understand the importance of in-page and off-page link building. The previous post discussed: when should you link sites with rel="nofollow" tag but great emphasis was made on the fact that all internal links should be kept do follow. Matt Cutts from Google “Webmaster help” has given a detailed video explanation on the use of rel="nofollow" tag and he has paid great stress on the fact that all links that point from one page on your blog to another whether they are hyperlinks or anchor tags must be kept dofollow.
Matt Cutts explaining Should Internal Links Use rel="nofollow"?
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