Notice: You should always make a backup. If you lose this key (by breaking or losing your computer and not having a backup for example), your encrypted data will be lost even if you remember your passphrase.

Tips: The secret key is itself encrypted, so it is only usable if one knows the passphrase. It is a good practice to store a backup in a different location. You can, for example, print it and mail it to a family member (along with a nice postcard!) and ask them to keep it somewhere safe. Or, even better, you can store it in a safe if you have one!