A file with the .mp4 file extension is an MPEG-4 video file format. MP4s are one of the more common video file formats used for downloading and streaming videos from the internet. It’s a highly versatile and compressed video format that also can store audio, subtitles, and still images.

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What Is an MP4 File?

MP4 files were created under the ISO/IEC 14496-12:2001 standard by the ISO/IEC and Motion Picture Experts Group (MPEG). Because of this, MP4 is an international standard for audio-visual coding.

Initially created in 2001, MPEG-4 Part 12 was based on the QuickTime File Format (.MOV). The current version—MPEG-4 Part 14—was released in 2003. MP4 is considered a digital multimedia container format—essentially a file containing a bunch of data that’s been compressed, The standard specifies how the data is stored within the container itself, but not how that data is encoded.

With the high degree of compression used in MP4 videos, this allows the files to be much smaller in size than other video formats. Reducing the file size doesn’t immediately impact the quality of the file, either. Almost all of the original quality is retained. This makes MP4 a portable and web-friendly video format.

While MP4 files can play audio, they shouldn’t be confused with M4A and MP3, as these are file formats that only contain audio.

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How Do I Open an MP4 File?

Because MP4 is a standardized file format for video, almost all video players support MP4. To open a file, all you have to do is double-click your video, and it will open with your operating system’s default video viewer. Android and iPhone natively support playback of MP4 as well—just tap the file, and you’ll be watching your video in no time.

Windows and macOS users can play MP4 files without having to install any third-party software. Windows uses Windows Media Player by default; in macOS, they’re played using QuickTime.

If, however, you prefer a different video player than either of those, changing the association of a file is a simple process on either Windows or macOS. And you most likely won’t even have to do that. When you install a new video playback app, the chances are high that the new app will claim the association with MP4 files during installation, unless specified otherwise.