Checkout
A checkout, in rrweb's sense of the word, is a scheduled re-baseline of a recording: the recorder takes a fresh full snapshot mid-session so the event stream contains periodic self-sufficient starting points instead of one ever-growing dependency chain. It bounds both seek time in replay and the blast radius of a corrupted event.
How it works
record() accepts checkoutEveryNth (a new full snapshot every N events) and checkoutEveryNms (every N milliseconds). The checkout documentation explains the segment behavior. Each checkout starts a new segment that can be replayed without anything before it. The cost is storage: every checkout adds a full snapshot's worth of bytes, so checkout frequency is a direct trade between seekability and size. The rrweb term has nothing to do with e-commerce checkout; a page about cart abandonment wants funnel analysis instead.
Where you encounter it
In recorder configuration, in storage planning, and in any player that offers fast seeking through long sessions. Live streaming setups also lean on checkouts so a viewer joining mid-session has a recent baseline to start from.