Sideloading describes the process of transferring files between two local devices, in particular between a 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.