Ink cartridges are small containers filled with liquid ink used in printers to produce text and images on paper. They come in various colors, typically including cyan, magenta, yellow, and black, allowing printers to create a wide range of colors through mixing. Each cartridge is designed to fit specific printer models, ensuring compatibility and optimal performance. When the ink in a cartridge runs low, it can affect print quality, leading to faded or incomplete images. Users can replace empty cartridges with new ones, and many manufacturers offer refillable cartridges or compatible cartridges as cost-effective alternatives to original products.