Sideloading apps involves installing apps on a device using methods other than the official app store. In the context of iOS devices, sideloading allows users to install apps that are not available on the Apple App Store. AltStore is a popular tool that facilitates sideloading on iOS devices.
There are several reasons why users may want to sideload apps. For instance, sideloading enables users to install apps that provide features or functionality not available in the App Store. Additionally, sideloading can be useful for testing and developing apps before they are submitted to the App Store.