Botnet

A bot, or a web robot is an automated malware program that scans blocks of network addresses and infects vulnerable computers. This allow hackers to take control of many computers at the same time and turn them into bots (also known as a zombie). Hackers typically use bots to infect large numbers of computers, which form a network or a botnet. Once the botnet is in your computer, it can be used in distributed denial of service (DDoS) attacks, proxy and also can be used to perform automated tasks over the Internet, without you knowing it (for example sending spam, viruses or stealing personal and private information such as bank credentials or credit card numbers).