In addition, e-mails can have files attached to them. This is one way information can be exchanged electronically. The problem is that when an attached file is opened, it can run a program called a "virus" or a "worm" without notifying the operator of the computer. If the creator of the attached file intends harm, opening that file can cause problems for the computer operator. There are several antivirus programs available that can scan e-mails as they to remove any attached files that carry viruses or worms.