These three are different types of backups

1. Complete Backup (Full Backup)

Everything gets copied

A complete backup copies ALL selected files and data, regardless of whether they have changed.

Example:

Imagine you have 100 GB of data.

• Monday: You back up all 100 GB.
• Tuesday: You back up all 100 GB again.
• Wednesday: You back up all 100 GB again.

Advantages:

• Easy to restore because everything is in one backup.
• Simple to manage.

Disadvantages:

• Takes longer.
• Requires more storage space.

Think: Complete = Copy everything.

2. Incremental Backup

Only changes since the last backup

An incremental backup only copies data that has changed since the most recent backup, whether that was a full or incremental backup.

Example:

• Monday: Full backup (100 GB).
• Tuesday: 5 GB of new or changed data.
• Wednesday: 3 GB of new or changed data.
• Thursday: 2 GB of new or changed data.

Each incremental backup only saves the changes since the previous backup.

Advantages:

• Faster backups.
• Uses less storage space.

Disadvantages:

• Restoring can take longer.
• You need the original full backup AND all subsequent incremental backups.

Think: Incremental = Changes since the last backup.

3. Differential Backup

Changes since the last full backup

A differential backup copies all data that has changed since the LAST FULL backup.

Example:

• Monday: Full backup (100 GB).
• Tuesday: 5 GB changed.
• Wednesday: 8 GB changed in total since Monday.
• Thursday: 10 GB changed in total since Monday.

Notice the difference?

Wednesday includes Tuesday’s changes, and Thursday includes both Tuesday’s and Wednesday’s changes.

Advantages:

• Faster restoration than incremental backups.
• You only need the full backup and the latest differential backup.

Disadvantages:

• Backup size grows over time.
• Uses more storage than incremental backups.

Think: Differential = Changes since the last FULL backup.

Visual comparison

Imagine you perform a full backup on Monday:

100 GB

MONDAY

Full backup

5 GB

TUESDAY

New changes

3 GB

WEDNESDAY

New changes

What gets copied?

Day	Incremental	Differential
Monday	100 GB	100 GB
Tuesday	5 GB	5 GB
Wednesday	3 GB	8 GB
Thursday*	2 GB	10 GB

*Assuming 2 GB of additional changes on Thursday.

The most important exam trick

Memorize these three sentences:

• Complete: Copies everything.
• Incremental: Copies changes since the last backup.
• Differential: Copies changes since the last full backup.