Sync, short for synchronization, is the process of keeping the same data up to date across several devices or services. Typical examples are browser bookmarks, photo libraries, notes, calendars and cloud file folders.
Why it matters
Sync lets you start on a phone and continue on a laptop. Under the hood, the service compares versions and copies changes in one or both directions. If two devices edit the same item while offline, the service must resolve the conflict, either by keeping the newest change, merging or saving both copies. Sync is also not the same as a backup: if you delete or corrupt a file, that change usually spreads to every device.
Example
A notes app stores your notes in the cloud. You edit one on your phone while offline. When the phone reconnects, it uploads the change with a timestamp, the service sends it to your laptop, and the laptop updates. If you edited the same line on both, the app may keep both versions and ask which to retain.
Common misconceptions
- Sync equals backup. A deletion also syncs.
- Sync is instant. It depends on connectivity, battery limits and the service.
- Two-way sync always keeps the right version. Conflicts need rules.
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