The Nintendo eShop is an online service for the Nintendo 3DS, Wii U, and Nintendo Switch that sells games, including classic emulated games (for play via the 3DS Virtual Console and Wii U Virtual Console), as well as providing access to game trailers, other video content, and demos for select games. DSiWare is also available for the Nintendo 3DS, with a few exceptions. Purchases are made with money instead of the points system used on the Wii and Nintendo DSi.
The current iteration of the eShop is divided into two virtual shelves. On the bottom shelf are lists of Best Sellers, Virtual Console games, Applications, Top Rated games, info on Retail titles, and possibly a patch for a popular game. The top shelf is split into left and right portions. The left portion contains such options as "Settings" and "Search," while the right section contains a number of categories, often whimsically inspired, containing a variety of games.
The eShop keeps a record of all games and applications ever downloaded onto a system. This means that if the data for a game is lost or deleted, the game can be downloaded again for free. However, the system is purely system-based as opposed to account-based, meaning that if the 3DS is lost, all of the games downloaded onto it are lost forever.
The Nintendo eShop updates every Thursday. Note that there are separate shops for each region, such as North America, Europe, and Japan.