t.co is Twitter’s short URL domain for links shared in tweets and posts.
Twitter introduced t.co in 2011 to wrap links posted through the service. The system shortened the visible address while also allowing Twitter to measure clicks and apply security checks. Links could therefore occupy a predictable amount of a post even when the destination URL was very long.
The domain is controlled by Twitter and is automatically used when links are processed through the platform. A t.co address usually redirects readers to the original destination, so it is not the same as a separate publishing website.
People often confuse t.co with bit.ly, a general-purpose URL-shortening service that users could choose independently. They may also mistake x.com for a shortener, but x.com is a web domain associated with the rebranded platform.