Also called: incr backup, incremental
In plain English
An incremental backup copies only the files changed since the last backup of any type — full, differential, or another incremental. It is the smallest and fastest backup to take, but restoring requires the full backup plus every incremental in the chain, applied in order.
Why it matters
Incrementals minimise backup time and storage, ideal for frequent (hourly) backups. The trade-off is restore complexity and fragility: a single missing or corrupt link breaks the chain, so retention and verification matter.