A codec is a compression standard that shrinks video files to manageable sizes while preserving quality. Common formats include H.264, H.265 (HEVC), VP9, and AV1. Your device must support a codec to play files encoded in it—incompatibility means the file won't play at all.
H.264 remains the industry standard and works everywhere. H.265 cuts file sizes nearly in half but requires newer hardware and software. Streaming services increasingly use H.265 for 4K content because bandwidth savings are substantial. Older devices may struggle or fail entirely.
Buying a device without checking codec support invites frustration. A cheap tablet might refuse to play videos you own. A premium phone might struggle with files your camera records. Specs lists bury this information, but it's worth hunting down before purchase.
Future-proofing matters here. AV1 is emerging as the next standard, offering further compression gains. Devices supporting multiple codecs—H.264, H.265, VP9, and AV1—remain viable longer. Checking codec lists takes five minutes and prevents expensive regrets.