Explain the concept of a snapshot in Redis and in which cases it is used.

In Redis, a snapshot is a mechanism for saving the current state of the database to disk as an RDB (Redis Database File). The snapshot is created periodically or on command to save data for recovery after restart or failure.

When Redis takes a snapshot, it records all keys and their values in a compact binary format. This allows for quick data loading at startup.

Snapshots are useful in cases of:

• Regular data backups.
• Fast recovery after failures.
• Data transfer between servers.

However, snapshots do not ensure the preservation of all intermediate changes, so for more frequent saving, the AOF (Append Only File) mechanism is used.