A computer virus is a small software program that can spread from one computer system to another and cause interferences with computer operations. A computer virus has the capacity to corrupt or to delete data on your computer and it can use an email program to spread the virus to other email addresses in your online address book. In the worst case scenario, it can even delete everything on your hard disk.
Unauthorized software that collects and transmits information over the Internet about a computer user without the user's knowledge or consent.
Spam is the abuse of email technology to send large quantities of unsolicited communications; this could be either commercial or malicious software such as viruses. Spammers harvest and compile bulk listings of email addresses by automated scanning of popularly used websites, or by intercepting the transmission of electronic mailing lists. Spam is illegal. The Federal Trade Commission (FTC) outlawed spam in the Controlling the Assault of Non-Solicited Pornography and Marketing Act of 2003 (CAN-SPAM Act) and has established strict protocols for the commercial use of bulk email. Most Internet service providers are working hard to protect their users from spam, but there are things you can do to reduce the amount of spam (malicious or otherwise) that you receive.