Keyword stuffing, over-optimization and its google penalties
Google doesn"t like black hat techniques as SEO keyword stuffing because those techniques focus on beating the algorithm of search engine rather than having a great user experience. Keyword stuffing is the practice of typing as many SEO keywords as possible onto the page. While over-optimization refers to the overuse of certain on-page or off-page optimization metrics. With the extreme use of some specific SEO techniques , the search engine becomes aware of the site and imposes a penalty.

Penalties of Keyword Stuffing and Over-Optimization
For many years, some webmasters have used keyword density as a benchmark to measure page optimization for specific search terms. Based on the keyword density logic, the more the keywords placed on the page, the better they will rank in search engine results for that keyword. However, if you place too many keywords on your website today, you can expect Google"s ranking to be banned due to over-optimization. As per some SEO experts, keyword stuffing is a type of over-optimization which can be prevented by considering quality above all. However, there are cases where some articles with these issues go unnoticed by the publishers simply because they are not aware of the things that they should be aware of.
Google Penalty is an inaccurate term that refers to what happens when a Google algorithm update negatively affects a site or page or manually penalizes a violation of a search engine"s webmaster guidelines. While a site"s sudden drop in search results ranking cannot always be easily explained and can be associated with several issues, you, as a business owner, can try to determine the nature of updating and modifying your site accordingly.
Keyword Stuffing Penalty
If Google founds your website to be guilty of using keyword stuffing its penalty will come in two forms
- Partial matches affect parts of your site
- Site-wide matches that affect the entire website
As a result of this penalty
- Your site will not be considered authoritative on a particular subject.
- Your website will be devalued, and if these methods persist, it will not work without indexing.

Over Optimization Penalty
The over-optimization penalty is a term used to refer to a change in Google"s search engine algorithm As a result, websites can be penalized for excessive SEO actions, including ranking degradation or even ranking down. Exclusion from the index of organic search engines. This poses the risk of losing search engine traffic.
The most important thing is to treat the problem carefully and find a solution to it. There is plenty of evidence for specific sanctions issues, so here"s what you need to know about common suspects and what to do when they do occur. Trying to make sure you"re getting the best content and doing a good job at marketing is the best way to ensure you maintain your rankings. However, if you are experiencing a sudden drop in traffic, take a close look at what has gone wrong and make sure to follow the instructions outlined in Google"s webmaster guidelines. So, you shouldn"t face any major issues with Google updates and penalties in the future.
Source: https://www.dotnek.com/Blog/Web/keyword-stuffing-over-optimization-and-its-go