Short answers, pulled from the story.
The Wii U sold 13.56 million units worldwide over its lifetime, making it Nintendo's lowest-selling home console ever. By comparison, Nintendo had originally expected the system to sell around one hundred million units, comparable to the Wii.
Nintendo attributed the Wii U's poor sales to a weak launch game lineup, limited third-party support, and marketing that failed to distinguish it from the original Wii. Nintendo's own Senior Product Marketing Manager acknowledged that pre-launch materials focused so heavily on the GamePad that some consumers mistook it for a Wii accessory rather than a new console.
Nintendo formally announced the end of worldwide Wii U production on the 31st of January 2017. The Nintendo eShop stopped accepting purchases on the 27th of March 2023, and online services shut down on the 9th of April 2024.
Mario Kart 8 is the highest-selling Wii U game, with 8.46 million units sold worldwide. Super Mario 3D World came second at 5.88 million units, followed by New Super Mario Bros. U at 5.82 million.
The Wii U GamePad is the console's primary controller, featuring a built-in 6.2-inch resistive touchscreen. The screen's contents are rendered on the console itself and streamed wirelessly to the GamePad, allowing players to continue games without a television in a feature Nintendo called Off-TV Play.
Reggie Fils-Aimé stated in January 2017 that the Wii U was "a necessary step" toward the Nintendo Switch, and that its commercial failure directly shaped how Nintendo designed the Switch's marketing to make the console's purpose immediately clear. The Switch retained and refined concepts introduced with the Wii U, including tablet-based play and a hybrid home-and-portable design.