All about Time Machine

This is much too large a topic for a single User Tip.

For a general overview and demonstration, see Apple's Time Machine Tutorial

For details, see the following web pages:

Time Machine - Frequently Asked Questions

Time Machine - Troubleshooting

Using Time Machine with a Time Capsule

Using Time Machine with an Airport Extreme Air Disk

Other Time Machine information:

How Time Machine works its Magic (overview of internal "works")

Time Machine vs. Clones and Archives (overview of different types of backup apps)