This definition explains the meaning of bots or botnets. Bots are programs built to perform a specific set of tasks automatically. These tasks could be something mundane like running a chat channel or more destructive like creating spam. Most illegal botnets are composed of computers already hacked and compromised without their owner’s knowledge. These are controlled via a single interface used by hackers or “herders”. These criminals use the huge accumulated power of botnets to engage in click fraud, i.e. clicking on ad banners to take money from advertisers who pay for each visit. They can also use them to saturate bandwidth and prevent access to websites for prolonged periods causing vendors to pay a ransom to get traffic flowing again.

Keylogging is another nefarious task that botnets are used for. They report keystrokes of thousands of users visiting websites to the herder who can use this info to access personal information and accounts. In the wrong hands, they can be used to hijack unsecured devices, send out spam, steal sensitive data, or stage a denial-of-service attack. Bot attacks can easily be avoided by: