01In plain English
A codec squeezes video or audio into a manageable file size and unpacks it again for playback. The file type, such as MP4 or MOV, is the container; the codec is what is inside. Some codecs are small and hard to edit, others are large and smooth to edit.
02How it works
Raw video would be too large to store or send, so a codec compresses it. The compressor, or encoder, looks for repeated information, such as a background that does not change between frames, and stores it once instead of thousands of times. It also discards details your eye is unlikely to notice. When you play the file, the decoder rebuilds the picture. Different codecs strike different deals. Some, like the ones used for streaming and phone cameras, make small files but need a lot of computer effort to decode, so editing feels sluggish. Others, made for editing, are bigger but play smoothly. The file extension, like MP4 or MOV, is only the box the codec comes in.
03Why it matters when you are choosing
The codec decides whether an editor can open your camera footage, how smoothly it plays while you edit, and which formats you can deliver.
04What to check
Check that the editor supports the codecs your camera records and the ones your clients or platforms ask for.
05Where you will meet it
06Common questions
What is the difference between a codec and a file format?
The file format, such as MP4 or MOV, is the container that holds the video and audio. The codec, such as H.264 or ProRes, is the method used to compress what is inside. Two files with the same extension can use different codecs, which is why one plays and the other does not.
Why does my video stutter in the editor?
Footage from phones and cameras often uses a codec that is compact but demanding to decode, and an editor has to decode many frames at once. Making lightweight copies, called proxies, or converting to an editing-friendly codec usually fixes the stutter.
Which codec should I deliver in?
It depends on where the video goes. Websites and social platforms generally accept widely supported codecs such as H.264, while broadcast and some clients ask for specific ones. Check the platform's or client's specification before you export, so you do not have to render twice.