HibPriyabarta, meta tags is one of the content tag in html. Search engines took in account the content of meta tags to determine what is content if the particular page on internet. Meta tags should be related to your pages' content. There are different limits on usage or no of characters for meta tags depending upon blogging platforms. You should use 200 characters to describe meta tags. It is good practice to have meta tag which contains other information like page of title and author name etc along with keywords.Regards, Sachin R. Kukale Editor-Forum
Keyword meta tags are not really considered important by Google anymore. However, there are various other search engines still use them. Moreover, Google could change their mind later and start considering it again. Since there are no penalties involved in using Keywords meta tags, I recommend using it to project some of the keywords in the page.
Make sure you are using only the keywords that are very relevant to the page and content. Use 5-6 keywords in the meta tag and not more than that.
I past keyword meta tags were chosen by many sites. It is considered one thing in html. But later good stopped using it. Its like making new things rule over here. Now keywords are most common things for articles and pages. The keywords regarding the page is more relevant for users to get through in it. Make through it your keywords are more valuable of your page. Your page can be validated even trough your keywords.