Compression is the process of reducing the file size of digital video or image content by encoding it in a way that removes or simplifies data without eliminating the content's essential visual information. It is necessary because uncompressed video files are prohibitively large for storage, streaming, and distribution, often measuring in hundreds of gigabytes for just minutes of footage at professional resolution.

Compression comes in two forms: lossless, which reduces file size without discarding any data and allows perfect reconstruction of the original, and lossy, which achieves much greater size reduction by permanently removing information deemed less perceptually important. Most video compression is lossy, using codecs such as H.264, H.265, or AV1 that analyse temporal and spatial redundancy across frames and remove detail that would not be easily noticed by viewers. The trade-off is that aggressive compression introduces artifacts such as blockiness, banding, and blurring, particularly in fast motion or detailed textures. Bitrate determines how much data is allocated per second of video, with higher bitrates preserving more quality at the cost of larger file sizes.

For creators working with AI-generated video, understanding compression is important when exporting final output. Over-compressing can erase the fine detail that generation models produce, while under-compressing results in files too large for practical use. Knowing the delivery platform's recommended settings allows creators to strike the right balance between quality and file size.