Most algorithm changes of Google are going against the technical SEO people that abused ranking factors

• Content Aggregation Scripts and Content Scraping ScriptsMajor source of duplicate content online. Often pestered with a variety of ads.

• Content Spinning ScriptsSometimes created as standalone desktop applications, sometimes as web-based applications with APIs, sometimes as CMS plugins, add-ons, extensions, or modules. Made to combat duplicate content issues, but often end up having bad grammar and low quality content.

• Article Directory ScriptsArticle directories used to be repositories of articles that you can search and find articles free to use for your own magazine or news website, online and offline. The benefit the author gets is simply recognition. Until the article directories started ranking themselves and spammers came in and just made their own article directories.

• Web Directory ScriptsOnline web directories are currently not as powerful as they were before. Probably the ones that still work are the ones for geographic location and are official citation sources. But everything else running the common opensource directory scripts, and are obviously made for links alone no long work.

• Submission ApplicationsMay be in the form of desktop applications, or a web-based tool, tool to submit to various places, from article directories, website directories, forum posting, blog commenting, social bookmarking and many more. In most cases, these postings can look as spammy as hell. Not because of the software, but how users were using it.

• Multiple Blog Administration SystemsCommon CMS plugins to manage sites multiple number of sites for blog networks. SEO using this technique just makes a network of blogs made for links alone. They use the multiple administration system to manage the blogs easier.

• Templates and Widget LinksAlmost every CMS has a template system, and in each one has the opportunity to display or even hide a link. Same is true with widgets on a CMS platform. Often disguised as a free theme or tool, to bait people to install it.