A key is supplied to the recipient so that they can then decipher the message. Keys for encryption algorithms are described in terms of the number of bits. The higher the number of bits - the more difficult that cryptosystem would be to break. Encryption can provide a means of securing information. As teachers, we are often called upon to handle sensitive student information.
Encryption is seen by many people as a necessary step for commerce on the internet to succeed.
Without confidence that net transactions are secure, people are unwilling to trust a site enough to transact any sort of business using it. Encryption may give consumers the confidence they need to do internet business. This proves that the sender was the true originator of the message, and that the message has not been subsequently altered by anyone else, because the sender alone possesses the secret key that made that signature. This prevents forgery of that signed message, and prevents the sender from denying the signature. E-mail is certainly not secure.