merits? They help identify what keywords apply to your site. They used to be highly recognized by Google some years back and became very popular. Now they add a little. With the combination of title tags, image tags, good KW density, use in description, and as in most other on page SEO techniques its good to take a sec and add them for sure.
Description tags appear on the bottom of the BLUE TITLE when you search for something. They're used to identify keyword densities by Google and also help to rank your pages for certain keyword.
The description displayed in SERPs will tell customers what product or service your website is selling.
This is a very important tag. This is the tag from where the search engines are extracts the information of your website.
A description tag is a place where you could add your keywords, could tell SE as well as users what your page is all about and when a potential user search for a keyword, your crisp description help you to get a click/visit.
Description Meta tag is play important role for ranking of a keyword at SERP. Description is define as summary of that particular webpage tell the Search Engine for which type product or category we are offer here, and always keep mind description tag get 160 character, actually most of serch engine chased only 160-170 character. For seo point of view bot of search engine give priority to tittle, description, alt and heading tag, so every person want place keyword in description for which they want ranking at SERP.