My friend Danielle keeps her all personal documents on her tiny 16 GB USB key. Since she always carries the USB key in her purse, there is no risk of losing it and the documents falling in the hands of someone else. If you also keep your important private files on your USB thumb drive, then you can go one step further an encrypt them so that nobody can access the documents even if they somehow get hold of the USB key itself. There are many free encryption tools that can be used to encrypt your files like AXCrypt, but a better encryption tool specifically designed for USB stick encryption is the SecurStick.
The SecurStick encryption utility uses the very strong AES 256 bit encryption cipher which is impossible (at present time) to break even for professional hackers. The tool can be downloaded from Mr. Matthias Withopf, the developer of this utility. It is completely portable and does not require installation of any sort. To start using the tool you can just copy it to the USB key and run SecurStick.exe from there. When it runs for the first time, it creates all the needed files in the same folder from where it is being run, opens a web browser window and asks you to create a new password. The password creation requirements are such that you cannot possibly end up using a weak password.
After the password has been created, it will automatically logon you to SecurStick. But for future uses, when you run the SecurStick tool, it will ask for the password so that you can login and access your encrypted and protected files.
After successful login, it will show the basic information about how you can access the files using the address http://127.0.0.2/X and how you can encrypt or decrypt them. You can access the list of files on this address or copy-paste it in File Explorer to access your secret files. It will also open the secret drive (A:) automatically in File Explorer where your encrypted content is stored.
In order to encrypt the files, you can copy the files in the secret drive. To decrypt the files on the secret drive, you can copy/move them to another folder on your hard disk or USB key. When you are done accessing or modifying your secret files, you can either log out from the web interface or just close the SecurStick.exe application window.
Conclusion: The SecurStick is a very strong encryption utility for encrypting files on your USB keys. It uses the industry strength AES 256 bit cipher making sure that only you will have access to your files.
You can download SecurStick from http://www.withopf.com/tools/securstick/.