Usually all your files like phone numbers, love letters, bank account data etc. are stored in plaintext on your computer's harddisk. All the data is accessible for everyone who has access to the harddisk. This is very bad in case someone you don't trust gets your harddisk. E.g. a thief that steals your notebook, or breaks into your house or company. If the thief has your disk he/she can also read all the files that where saved on it, no matter whether you have a login password or not - the files are always stored in plaintext.
The CryptoBox brings easy-to-use data encryption to your computer. This works out of the box and does not need complicated configuration steps.
Here comes a small usage example for the CryptoBox with an obsolete PC as a fileserver:
Boot up the old PC with the CryptoBox live-CD. Now you can access it with your browser via the network. Then you partition and reformat the harddisk of the old PC with encryption support. Therefore you provide a passphrase. This is all done through the user friendly webinterface. You can also plug in an external harddisk and use this to store your encrypted data. Afterwards you copy your sensitive data over the local network to the CryptoBox. It is stored on its harddisk in a secure way. Nobody can access your data without the right passphrase.