Once you start using Lightroom seriously you should start to think about backups. It's possible to get Lightroom to back up your catalog periodically, but this is only the catalog and not the photos themselves.

Backing up to the same disk that your catalog is on doesn't really help in the worst-case scenario, when the entire disk is lost or damaged. In this situation you will want to have what's called an "off-line" backup - that is, one that exists outside of your computer.

One way is to buy a good-sized external disk and back up to that. Both Windows and Mac offer built-in backup options, and if you buy a new external disk then there is a good chance that it will come with backup software included.

The safest option is to backup to a server somewhere else, or "the cloud". While no service is infallible, data loss with a cloud backup provider is rare enough to make the news so they're as safe as it's possible to get. There are various options out there, the highest profile ones being Rackspace and Amazon, but they work out to be fairly expensive if you read the small print, especially if you're backing up and storing large amounts. It's usually possible to get better deals from resellers, such as www.gotabackup.com . Look for one that has live support so that you've got someone to talk to if you need to.

Once you've got all your photos and the catalog stored somewhere else, even if the worst happens you don't need to worry about losing your photos and Lightroom catalog.