The word 'keygen' means a small program that can generate a cd key, activation number, license code, serial number, or registration number for a piece of software. KeyGen is a shortened word for Key Generator. A keygen is made available through crack groups free to download. When writing a keygen, the author will identify the algorithm used in creating a valid cd key. Once the algorithm is identified they can then incorporate this into the keygen. If you search a download site for Backuptrans Keygen, this often means your download includes a keygen.