Video Containers vs Codecs
A common confusion: the file extension (.mp4, .mkv) is a container — a wrapper around the actual video and audio data. The codec (H.264, H.265, AV1) is what actually compresses the video. One container can hold many codecs.
MP4 (MPEG-4)
The most compatible format. Works everywhere — phones, TVs, web browsers, social media. Use H.264 codec inside MP4 for maximum compatibility. H.265/HEVC inside MP4 gives better quality at smaller sizes but less compatibility.
MKV (Matroska)
An open container that supports multiple audio tracks, subtitles, chapters, and virtually any codec. Popular for archiving and home media servers (Plex, Jellyfin). Not supported natively by social platforms — always convert to MP4 before uploading.
AVI (Audio Video Interleave)
Microsoft's old format from 1992. Large file sizes, no streaming support. Only use if legacy software requires it. Otherwise avoid completely.
MOV (QuickTime)
Apple's format. Great on Mac and iPhone. Compatible with most modern software but convert to MP4 before sharing with Windows users.
WebM
Open-source, royalty-free. Designed for web browsers. Great for embedding video on websites. Not ideal for offline storage.