Sideloading describes the process of transferring files between two local devices, in particular between a personal computer and a mobile device such as a mobile phone, smartphone, PDA, tablet, portable media player or e-reader.
Sideloading typically refers to media file transfer to a mobile device via USB, Bluetooth, WiFi or by writing to a memory card for insertion into the mobile device, but also applies to the transfer of apps from web sources that are not vendor-approved.
When referring to Android apps, "sideloading" typically means installing an application package in APK format onto an Android device. Such packages are usually downloaded from websites other than the official app store Google Play. For Android users sideloading of apps is only possible if the user has allowed "Unknown Sources" in their Security Settings.[1]
When referring to iOS apps, "sideloading" means installing an app in IPA format onto an Apple device, usually through the use of a computer program such as Cydia Impactor[2] or Xcode. On modern versions of iOS, the sources of the apps must be trusted by both Apple and the user in "profiles and device management" in settings, except when using jailbreak methods of sideloading apps. Sideloading is only allowed by Apple for internal testing and development of apps using the official SDKs.[3]