What about other search engines that use them? Hang on while I submit my site to those 75,000 engines first [sarcasm!]. Yes, ten years ago early search engines liked looking at your meta-keywords. I’ve seen OPs in forums ponder which is the best way to write these tags – with commas, with spaces, limiting to how many characters. Forget about meta-keyword tags – they are a pointless waste of time and bandwidth.

So what are the rules of thumb here? First and foremost, it’s very important that your content is easy to read. Of course, you should use your keywords in your text, but don’t stuff your keywords in almost every sentence. In general, if 1 or 2% of all words of your copy, is your keyword, then you’re not overdoing it. Make sure your keywords are well-distributed throughout your text. Don’t put all your keywords in the first paragraph thinking you’re done with that part of the optimization. Naturally spread the keywords throughout your page or post. Use your keywords in a subheading or a couple of subheadings, depending on the length of your page or post. And use the keyword in your page title, first paragraph and your meta description. You can find all of these recommendations in the SEO analysis of Yoast SEO.
Search engines may penalize sites they discover using black or grey hat methods, either by reducing their rankings or eliminating their listings from their databases altogether. Such penalties can be applied either automatically by the search engines' algorithms, or by a manual site review. One example was the February 2006 Google removal of both BMW Germany and Ricoh Germany for use of deceptive practices.[54] Both companies, however, quickly apologized, fixed the offending pages, and were restored to Google's search engine results page.[55]
QUOTE: “If you want to stop spam, the most straight forward way to do it is to deny people money because they care about the money and that should be their end goal. But if you really want to stop spam, it is a little bit mean, but what you want to do, is sort of break their spirits. There are lots of Google algorithms specifically designed to frustrate spammers. Some of the things we do is give people a hint their site will drop and then a week or two later, their site actually does drop. So they get a little bit more frustrated. So hopefully, and we’ve seen this happen, people step away from the dark side and say, you know what, that was so much pain and anguish and frustration, let’s just stay on the high road from now on.” Matt Cutts, Google 2013
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