Elementary OS is a Ubuntu-based linux distribution. Some of the features that make distribution unique are a custom desktop environment called Pantheon and a custom software center.
The latest version of the project is the elementary OS 5.1 "Hera", which comes with updated packages, a new login screen and an onboarding application to guide new users in the available functions.
"The recently redesigned login and lockscreen greeter looks and works better, but it also fixes many issues that have been reported with the previous greeter, such as focus problems, HiDPI and localization problems. The new design of the Hera version responds to the comments of Juno users and adds some new features. It will always display usernames for all users, show users backgrounds like cards so you can find them more easily especially those who do not have avatars, notify when Caps or Num Lock are on and have a 'Log In' screen as Guest 'very special when enabled.
The new Onboarding application brought by the Hera version introduces the basic functions to the users and helps them to perform some common tasks after the first connection to the operating system, such as the management of privacy settings. ”
More details and more screenshots can be found at announcement of the new version.