Xbox Series X|S are the home video game consoles developed by Microsoft. They were both released on November 10, 2020, as the fourth generation Xbox, succeeding the Xbox One. Along with Sony's PlayStation 5, also released in November 2020, the Xbox Series X|S consoles are part of the ninth generation of video game consoles. Rumors regarding the consoles first emerged in early 2019, with the line as a whole codenamed "Scarlett" and consisting of high-end and lower-end models codenamed "Anaconda" and "Lockhart" respectively; "Anaconda" was teased by Microsoft during E3 2019 under the codename "Project Scarlett", and unveiled during The Game Awards in December as Xbox Series X. On September 8, 2020, Microsoft unveiled the lower-end model, Xbox Series S. As with the Xbox One line, the consoles utilize an AMD CPU and GPU. Both models feature a new storage architecture based around solid-state drives to reduce loading times, support for hardware-accelerated ray-tracing and spatial audio, the ability to convert games to high-dynamic-range rendering using machine learning (Auto HDR), support for HDMI 2.1 variable refresh rate and low-latency modes, and updated controllers. Xbox Series X was designed to nominally render games in 2160p (4K resolution) at 60 frames per second (FPS). The lower-end, digital-only Xbox Series S, which has reduced specifications and does not include an optical drive, was designed to nominally render games in 1440p at 120 FPS, with support for 4K video scaling and ray tracing. Xbox Series X|S are backward-compatible with nearly all Xbox One-compatible games and accessories (including Xbox 360 and original Xbox games that were made backward-compatible with Xbox One), with the ability for games to automatically benefit from the performance and visual improvements enabled by the newer hardware. At launch, Microsoft encouraged a "soft" transition between generations similar to PC gaming, offering the "Smart Delivery" framework to allow publishers to freely and automatically provide upgraded versions of Xbox One titles with optimizations for Xbox Series X|S. Publishers are not required to use Smart Delivery and may publish Xbox Series X|S-exclusive titles if they so choose. Developers such as EA do not use Smart Delivery and prefer to sell separate Xbox One and Xbox Series X|S versions. Xbox Series X/S received praise from critics for the hardware specifications of the Series X in comparison to older Xbox One models, and Microsoft's emphasis on cross-generation releases, but believed that the games available at launch did not fully leverage the hardware capabilities of the consoles. Microsoft has not officially released sales data for the Xbox Series X/S but stated on July 27, 2021, that they were the fastest-selling Xbox models to date, and it was estimated that Microsoft had shipped at least 14.6 million units of the two consoles worldwide by June 2022.