3GPP is a multimedia file format that is primarily intended for storing audio and video files, as well as their transfer over 3G networks. This rather sophisticated technology was developed by the consortium Third (3rd) Generation Partnership Project, whose name gave the abbreviated name of this format (3GPP). The developer created this format so that the third generation of mobile phones can use smaller files. Another task is to unify the format of audio and video files for compatibility with various mobile devices. 3GPP files can be played not only on 3G phones, but also on 2G or 4G phones.
MKV is an open container format for audio and video data created by Russian developers. The name of the format originates from the name of the project - Matroska (Matryoshka) with the addition of the first letter of the word Video. This format is considered an alternative to the much more popular AVI, but has not yet reached such a scale of distribution. MKV files are quite common among owners of fairly old mobile devices with Symbian OS and at the same time among those who prefer to watch video in FullHD, since MKV has good dynamics of transmitting video / audio streams. MKV with a wide range of features, in particular, storing audio tracks in different languages, is easy to edit, there are no freezes in large files.