Title tags and meta descriptions are on-site HTML elements which reflect the content of your page, and are shown in SERPs and browser tabs as text.
With Google increasing the width of the SERP to 600px, the length of title tags falls between 40 and 50 characters (best practices) while meta descriptions should be a maximum of 160 characters.
Titles display what your page is about to both visitors and search engine crawlers, while meta descriptions summarize the content of your page. Your title tags and meta descriptions must include the keywords you are trying to rank for, for example, “cheap hotels in Las Vegas” (title tag includes a keyword and locality).
Titles and meta descriptions must be unique, compelling and descriptive, as this can affect click-through rates from search results to your page.