MP4 (MPEG-4 Part 14) is a container format based on the ISO Base Media File Format (ISOBMFF/MPEG-4 Part 12), similar to QuickTime.
Widely used for converting videos to optimized MP4/M4V formats with strong compression (e.g., H.264), recommended for balancing file size and quality. g114.mp4
Discussion about posting (videos or) .gifs on this forum - Page 2 MP4 (MPEG-4 Part 14) is a container format
It consists of "boxes" (or atoms). The first 8 bytes are a box header (4 bytes for size, 4 bytes for type). 4 bytes for type).