• Viruses, worms, and Trojan horses. A computer virus is a type of malicious software program (“malware”) that, when executed, replicates by reproducing itself (copying its own source code) or infecting other computer programs by modifying them. A computer worm is a stand-alone malware computer program that replicates itself in order to spread to other computers. A Trojan horse, or Trojan, is any malicious computer program that is used to hack into a computer by misleading users about its true intent.
  
• Spoofing or phishing. Phishing is the attempt to obtain sensitive information such as usernames, passwords, and credit card details (and, indirectly, money), often for malicious reasons. Often the sender of the electronic communication is disguised as a trustworthy entity.
  
• Denial-of-service attacks. A denial-of-service attack (DoS attack) is a cyber attack in which the perpetrator seeks to make a machine or network resource unavailable to its intended users by temporarily or indefinitely disrupting the services of a host connected to the Internet.
  

The low cost and rapid delivery of electronic communication makes it the preferred method of communication for both business and consumers, but there can be hidden hazards and costs. The following are common ones:

• Electronic communications are forever. Electronic messages are permanent (this includes communications such as email and also audio recordings such as voice mail). Even if a person deletes the communications from his or her own server or account, there are generally other servers that still hold this information. One way that these types of communications live in perpetuity is when they are sent or forwarded to multiple individuals.
• Someone may be watching. In many cases, confidential information is leaked by someone else sifting through his or her messages. The culprit may be a disgruntled employee or even a competitor. Workstations left unattended, employees remaining logged on to networks and email accounts when they are away from their desk, and even sharing passwords with coworkers all make it easy for prying eyes to see information not intended to be shared.
• Innocent messages can still harm you. Civil litigation lawyers will warn you that even innocent messages can get you in trouble you if they are taken out of context. When a person writes an email or text, he or she may have only one intent or meaning in mind. However, messages can be misconstrued to apply to a completely different scenario.
• Email avalanche. Managers, in particular, are vulnerable to relying on email too heavily for communication. People use email because it’s quick and easy, and they can send the same information to a lot of people at the same time. This can lead to information overload and misunderstandings by recipients, however. Words alone account for only 7 percent of communication,^[1] so it’s important for managers to be aware of the limitations of email in getting their messages across.