What is the name of Twitter's premium subscription service launched in 2021?

Twitter's premium subscription service launched in 2021 was Twitter Blue. Twitter announced the paid service on June 3, 2021, initially introducing it in Australia and Canada before expanding it to other markets.

Twitter Blue offered subscribers extra features rather than creating a separate social network. Early benefits included an Undo Tweet option, bookmark folders, reader mode, app color themes, and dedicated customer support. The service reached customers in the United States on November 9, 2021.

The name later became confusing because Twitter was rebranded as X in 2023. Twitter Blue was first referred to as X Blue and was subsequently renamed X Premium. That later branding does not change the answer for a question specifically asking for the service launched in 2021. Twitter Pro, Twitter Plus, and Twitter Gold were not the official name of that original subscription product.