Sidecar File
A small companion file stored next to a raw file, holding edits and metadata that cannot safely be written into the raw itself.
Measured in
KB
In depth
Proprietary raw formats are undocumented and often checksummed, so writing into them risks corruption — the sidecar exists to avoid that. The practical consequence is that raw files must always be moved together with their sidecars, since separating them silently discards every edit.
Examples in practice
Moving 500 raw files without their XMP sidecars leaves an entire shoot's edits behind.