Bitrate

Bitrate is how many bits of data the encoder spends on each second of video, usually written in Mbps. Spend more and the picture keeps its fine detail; spend less and the encoder starts throwing detail away, which shows up as blocking in shadows, mush in grass and confetti, and banding across a clean sky. File size is roughly bitrate times duration, so it is also the dial that decides whether your upload finishes today.

Two modes matter. CBR holds a constant rate (broadcast, live streaming, anything with a fixed pipe). VBR lets the encoder spend more on hard shots and less on a static talking head, usually two-pass for better allocation. CRF and other constant-quality settings are a third rate-control mode in the encoder, not a codec of their own: they flip the dial around so you pick a quality target and let the bitrate float, which is usually the smarter choice for web delivery.

Gotcha: bitrate is not quality on its own. It only means something relative to resolution, frame rate, and codec. 10 Mbps is generous for 1080p30 H.264, thin for 4K60, and wasteful compared to what AV1 needs for the same look. Also remember YouTube, Instagram, and everyone else re-encode your upload, so hand them a high-bitrate master and let them do the squeezing rather than pre-crushing it.