Meta keywords tags are a set of tags that have keywords to tell the search engine what it is about or what the content or theme of a website is. They are invisible to users. Search engines currently ignore them for ranking purposes.
Here is a small hint about this question: in September 2009, Google officially confirmed what was already a reality for years; this reality is that Google does not use meta keywords tag in websites' ranking. In October of the same year, the Yahoo search engine also gave the news that they did not use the meta keywords tag here. It must be said that this was not entirely true since they do use them, although they do not give any benefit. For 2014 the search engine Bing also declared that the meta keyword tags had no value in terms of SEO.
Although they could have some value in terms of contextual ad systems or as a signal to crawlers looking for topics to point to in the network. Still, in reference to the searches, they were only as reinforcement. It was even understood that using them incorrectly could be counterproductive because they are seen more like spam than a sign of classification.
So the most sensible answer to the question is that time should not be wasted on meta keywords tags, and the time that must be invested in thinking about the words to put on the tag is better spent thinking about the content or also using it in the keyword search.
There are doubts about using meta keywords tag and whether their use can actually damage a website.
It is generally believed that including them in a website can lead to Google's penalties since their usefulness is null.
The reality is that the fact of using them does not show any type of problem, and search engines do not impose any type of punishment on web pages that choose to include these tags in their lines of code.
They are simply invisible to search engines and are not even taken into account at all.
Despite being currently in total disuse, it is good to illustrate with an example how they are used and what they are.
The reality is that there are still websites that currently include the Meta keywords tag in their lines of code.
If you want to add a Meta keywords tag on a website, you must include the following line in the code: <meta name="keywords" content="keyword">
Otherwise, in the WordPress program, there are two plugins with which this type of tags can be applied:
Suppose the decision is made to implement this type of tag on the web, despite what was explained in the previous points. In that case, the recommendation is not to use many words and pay special attention to spelling.