Nintendo Switch Online is a service that offers a suite of features for Nintendo Switch handheld game console which requires the user to purchase a subscription for 20$ annually. Since its launch on September 19, 2018, the online service has gathered around 9.8 million users.
With Nintendo reporting 34 million units of Switch sold worldwide, this number comes close to 1/3rd population of total user-base.
Nintendo Switch Online features include online multiplayer, cloud saving, voice chat, access to a library of Nintendo Entertainment System (NES) games, as well as other promotions and offers. Following a period where some of its features were available to all users at no charge, but after the official launch, these features were made exclusive to Nintendo Switch Online.
Unlike Xbox Live and PlayStation Plus, Nintendo Switch Online does not offer free games every month, but Nintendo Switch Online does offer a roster of free classic NES titles.
With Nintendo denying launch of upgraded model at E3, this number is sure to rise. As the Switch grows its library of games also grows, with many developers/publisher now looking at it as potential future console many games are in works for Switch either new or ports.