QUOTE: “So it’s not something where we’d say, if your website was previously affected, then it will always be affected. Or if it wasn’t previously affected, it will never be affected.… sometimes we do change the criteria…. category pages…. (I) wouldn’t see that as something where Panda would say, this looks bad.… Ask them the questions from the Panda blog post….. usability, you need to work on.“ John Mueller, Google.
When would this be useful? If your site has a blog with public commenting turned on, links within those comments could pass your reputation to pages that you may not be comfortable vouching for. Blog comment areas on pages are highly susceptible to comment spam. Nofollowing these user-added links ensures that you're not giving your page's hard-earned reputation to a spammy site.
SEO stands for ‘Search Engine Optimization’. It’s the practice of optimizing your web pages to make them reach a high position in the search results of Google or other search engines. SEO focuses on improving the rankings in the organic – aka non paid – search results. If you have a website and you want to get more traffic, it should be part of your marketing efforts. Here, I’ll explain what SEO is and how we approach it at Yoast.