A title tag is an HTML element that specifies the title of a web page. It appears in the browser tab and is often used by search engines like Google to display the page's title in search results. Title tags help users understand the content of a page and can influence click-through rates. Title tags should be concise, typically between 50-60 characters, and include relevant keywords related to the page's content. This practice not only aids in search engine optimization (SEO) but also enhances user experience by providing clear and informative titles for each page on a website.