Description Tags provide a concise description of a web page, within a Search Engine Results Page (SERP).
If a Description tag is missing, the SERP result may show random wording drawn from the web page.
Since 2009, Description tags have not counted as Google ranking factors.
However, because they can make your search engine listing look better, they are important.
To put it another way, well-written Description tags will help you to get more visitors to your website as they increase the chances of a click.
When you search for something in Google, underneath the adverts (if there are any) you will see organic search engine rankings.
The ‘headline’ of each result is generated by the Title Tag of the web page.
The text underneath this is the Description Tag (if such as tag exists for that page).
On this basis, the description tag text is like the body copy of an advertisement.