- The "-30 penalty"

- The "-950 penalty"

- Index Exclusion

There has been a lot of debate about whether the drop of a website's rank by 30 or 950 spots in Google is really a penalty for unethical SEO tactics, or is it simply a result of an agorithm shift (and the particular site just didn't measure up against the new algorithm so it dropped).

Many people insist there is no penalty (except Exclusion for really blatant "Black Hat" techniques), and rather it is all about Filters. If you do something that triggers a filter your site won't rank as highly. Whether you call it a filter or a penalty, the results are the same. If you don't follow best practices, sooner or later your site will be penalized or filtered out of the top rankings.

It is widely accepted that the -30 penalty affects the whole domain, however the -950 penalty only affects specific URLs for specific keywords.

Rather than actually moving your site back by precisely 950 spots, I think it is more likely that you are just going to be banished to the end of the results. It also appears to be specific to certain search queries. A site may go from first page to last page in the SERPs (search engine results page) on one keyword, and still hold a top ranking on another keyword.

Both of these penalties are associated with shady optimization practices. Some say these penalties happen when there is keyword stuffing, while some others say that these penalties are because of shady link building practices.

It is widely believed that getting too many links within a short time span and with similar anchors can raise red flags with Google. I personally believe this to be true and always tell people to be careful with their link acquisitions. Acquire links at a consistent, natural pace.

Google doesn't believe that sites will naturally gain large numbers of links quickly, unless a software is being used and the system is being gamed. Google looks for what would naturally occur. Most people gain links over time as content spreads and it is rare to gain large numbers of links naturally in a short time period.

Another penalty is the Index Exclusion penalty or a complete ban. When a site gets hit with this Google throws the entire site and all their pages out of the Index.

This is reserved for sites that severely violate the quality guidelines and adopt black hat methods such as cloaking and doorway pages.

How Do You Avoid These Penalties?

- Build your website keeping the users in mind instead of the search engines.

- Do not stuff keywords in the page title, description, alt tags and in the content.

- Do not link out to link farms and sites engaged in link manipulation practices.

- Be consistent in building links and vary your link anchors as much as possible.

- Avoid cloaking & doorway pages

With proper on-page optimization and by following the tips above, your site should fare well in the engines and you should have nothing to worry about.