What Is A Title Tag?
The title tag should describe the content of your webpage with keywords that are relevant for the page. A title tag should consist of 65 characters at most, white space included. Google sometimes lists titles which contains some more characters than 65, but if you want to be sure to not get a title that ends with "..." in the search result - use 65 characters only. The title tag is shown at the top of your web browser window.
Importance
The title tag is the most importance HTML tag on your web page as it is one single factor that can give your web page better positions in the search results. Writing a descriptive title is very important as it gives weight and relevance to the keywords you want to rank for.
Good Titles Stimulates Clicks
You will also get another advantage other than relevance to certain keywords - people tend to click more on well written titles. As an example: If search result #1 and #2 uses bad titles and descriptions and you are number #3 your chances of getting a click and more visitors increases.