favorite lists for quick access. Players can add non-Steam games to their libraries, allowing the game to be easily accessed from the Steam client and providing support where possible for Steam Overlay features. The Steam interface allows for user-defined shortcuts to be added. In this way, third-party modifications and games not purchased through the Steam Store can use Steam features. Valve sponsors and distributes some modifications free of charge; and modifications that use Steamworks can also use VAC, Friends, the server browser, and any Steam features supported by their parent game. For most games launched from Steam, the client provides an in-game overlay that can be accessed by a keystroke. From the overlay, the user can access his or her Steam Community lists and participate in chat, manage selected Steam settings, and access a built-in web browser without having to exit the game. Since the beginning of February 2011 as a beta version, the overlay also allows players to take screenshots of the games in process; it automatically stores these and allows the player to review, delete, or share them during or after his or her game session. As a full version on February 24, 2011, this feature was reimplemented so that users could share screenshots on websites of Facebook, Twitter, and Reddit straight from a user's screenshot manager. Steam's "Big Picture" mode was announced in 2011; public betas started in September 2012 and were integrated into the software in December 2012. Big Picture mode is a 10-foot user interface, which optimizes the Steam display to work on high-definition televisions, allowing the user to control Steam with a gamepad or with a keyboard and mouse. Newell stated that Big Picture mode was a step towards a dedicated Steam entertainment hardware unit. With the introduction of the Steam Deck, Valve began pushing the new Big Picture mode based on the Steam Deck UI in beta testing in October 2022, and full release in February 2023. In 2012, Valve announced Steam for Schools, a free function-limited version of the Steam client for schools. It was part of Valve's initiative to support gamification of learning for classroom instruction. It was released alongside free versions of Portal 2 and a standalone program called "Puzzle Maker" that allowed teachers and students to create and manipulate levels. It featured additional authentication security that allowed teachers to share and distribute content via a Steam Workshop-type interface, but