Title tag: an HTML element that defines the title of an online document (web page).  The title tag is the second most critical component of on-page SEO (content is the most important component).

The title tag appears in an internet browser, the SERPs (search engine result pages) and  external websites.

Internet Browser

The title tag can appear at the top of some website browsers as well as on the top of the tab area if you’re using multiple tabs inside your browser.
title tag example


SERPS (search engine results pages)

title tag example in serps

title tag example on bing

How long can a title tag be?
Typically a maximum amount of 70 characters will display in the search results. It is better to place the important keywords at the beginning of the title tag. When you do a search on Google and/or Bing, you will see your title tag appear at the top of your listing in the SERP. Each search engine uses different character counts to display, you will notice in the two graphics above that Bing (the bottom image) is displaying fewer characters in the title tag then Google does in this example.

Make sure your title tag is as relevant to the page content as possible in order to help the search engines choose the best page of your site that matches the users query.