Dogs in warfare have a long history starting in ancient times. From war dogs trained in combat to their use as scouts, sentries and trackers, their uses have been varied and some continue to exist in modern military usage.
Encryption is the coding or scrambling of information so that it can only be decoded and read by someone who has the correct decoding key. Encryption is used in secure Web sites as well as other mediums of data transfer. If a third party were to intercept the information you sent via an encrypted connection, they would not be able to read it.
Encrypting File System is a filesystem-level encryption, which means that the files and folders are encrypted with a password. I will not go into the details of the encryption with the EFS Keys and public/private key exchanges, because it is an immense issue that can not be explained in an article.