Since the beginning of the internet there have been spammers intent on defrauding users and generally spoiling things for legitimate businesses. Because you may be a legitimate business attempting SEO but unaware of its best practices – or wondering why Google issued you a manual spam penalty – below is a list of spam types as defined by Google.

• Pure Spam – A term for sites that repeatedly or blatantly violate Google’s webmaster guidelines. This is the worst of the worst: auto-generated gobbledygook, content scraping, link farming, cloaking, malware, etc.

• Cloaking – This is when a site presents different content to a search spider than to a user. Google will interpret it as a safe site, but when the user clicks on the link they are sent to a spam wasteland.

• Hidden Text, Keyword Stuffing – See How Does PageRank Work?.

• User-Generated Spam – Or, “why you need to put filters on your comments.” Any part of your site that allows user input (forum pages, comments sections, guestbooks and user profiles) is vulnerable to spammers. The best way to combat this is to use spam blocking software in your content management system, and hire a forum moderator.

• Thin Content – Low quality pages with little value to site visitors and readers; auto-generated or copied content.

• Unnatural Links – Any kind of link manipulation: link wheels, link farms, link schemes, etc. Don’t do it. It’s not worth it.

• Hacked Site – You may be all sweetness and light. That hacker that shanghaied your site to display spam content and links? Not so much. Once you’ve cleaned your site and eliminated the hack, inform Google and it will review your site for legitimacy.