What a title tag does in search, social, and browsers
The title tag is the single most weighted on-page element you control. It's the blue clickable line in Google results, the tab label in the browser, the default name when someone bookmarks the page, and the fallback headline when your page gets shared without Open Graph tags.
Google rewrites titles roughly 60% of the time when it thinks yours doesn't match the query or is stuffed with boilerplate. You reduce rewrites by keeping the title specific to the page's actual content, front-loading the term people search, and skipping repeated brand-and-category prefixes on every URL.