Backup window
The period available for backups to run without affecting normal operations.
As data grows, jobs eventually run past the window and into the working day, competing with users for the same disk and network capacity.
The usual answers are incremental strategies, deduplication, and snapshot-based backup that captures a consistent image quickly rather than reading everything sequentially.
Where this comes up
Backup window sits inside our backup and disaster recovery work. If you are trying to work out what this means for your own environment rather than in the abstract, that is the page worth reading next, and a short call will get you a straight answer faster than either.