Ink cartridges are small containers filled with liquid ink used in inkjet printers. They come in various colors, typically including black, cyan, magenta, and yellow, allowing for a wide range of printing options. When the printer is in use, the cartridge releases ink onto paper to create text and images. These cartridges can be either original equipment manufacturer (OEM) products or compatible alternatives. OEM cartridges are made by the printer's manufacturer, while compatible cartridges are produced by third-party companies. Users should choose based on quality, cost, and compatibility with their specific printer model.