I have recently discovered TrueCrypt, a great open source data encryption tool that has recently gained the attention of security experts Bruce Schneier and Steve Gibson. TrueCrypt is cross-platform, meaning it runs on various versions of Linux and Windows (an OS X version is in the works). With TrueCrypt, you can create a folder or volume that encrypts/decrypts data on the fly in a seamless way. Further, TrueCrypt volumes are platform independent, so you can encrypt a volume in Linux and then decrypt it in Windows.
Data encryption is useful for many situations. I use it to encrypt my research data and documents on my laptop. As a researcher, I am required to keep confidential any personal data I may collect in my studies. With TrueCrypt, I can store potentially sensitive data on my laptop without fear of data theft. There are many other practical reasons why someone may wish encrypt his/her documents.
The fact that TrueCrypt is open source is a strong benefit. One advantage TrueCrypt has over Microsoft’s optional encryption scheme for Windows and other commercial solutions is the peer review of source code. The security and encryption communities have full access to the TrueCrypt source code, making any vulnerabilities or errors in the implementation of encryption algorithms plainly visible and more readily remedied.