Title Tag, URL and Meta Description is the initial information what users (searchers) over Search Engines is looking after. SERPs (Search Engine Results Pages) shows snippet which includes Title Tag, URL of your Website Page and Meta Description.
The first and most important part of on page seo technique is title tag. A user searching for your keyword will see your site's link highlighted in the search engines if your page's title came for the phrase as they searched for. The significantly increases click through and even give you more traffic than those who rank above you if their title are not optimized.
The Title tag generally used to tell user's about your business and its tell serach engine what is your page topic. It's help both user & search engine to find out what user looking for and what search engine have to serve you.