Title: The title of a webpage or site is used to describe a document's contents. A title is often one of the most important parts of a page-based SEO plan. Good titles also encourage social sharing, optimize the look of your site on a browser, and clean up the appearance of external links to your site.
A good SEO title is unique to the page and reasonably descriptive without being excessively long. The optimal format, with some exceptions, is primary keyword - secondary keyword | Brand Name.
All that needs to be done to make titles unique is make sure titles aren't identical on every page of a site.
As for descriptive, titles should explain what important or central ideas are covered on the given web page or document.
The ideal length for an SEO title is 8-10 words, though shorter titles are acceptable. Google usually displays the first 50-60 characters of a title on its search engine result pages, and 55 characters will usually make your titles display correctly. Structure is also important. Important words should be placed near the beginning of the page title.
Good titles benefit your site's relevancy, user experience, and search engine results. Titles should be informative, honest, and reflective of your brand.