A bot is automated software that performs repetitive actions at machine speed. Bots can be harmless, such as search crawlers or monitoring agents, but in cyber security they often matter because automation scales an operation far beyond what a human can do manually. A single bot, or a botnet of many bots, can generate traffic, create accounts, submit forms, scrape content, or inflate usage metrics with little delay and low cost.
In attacks, bots are used for spam, credential stuffing, ad fraud, fake clicks, and stream manipulation, where automated activity is made to look like real user behavior. Defenders look for bot patterns such as abnormal timing, repeated device fingerprints, shared network sources, and impossible growth rates. Detection systems may combine anomaly detection, rate limiting, authentication checks, and behavioral analysis to separate legitimate users from automated abuse. In integrity-focused systems, the risk is not only service load but also corrupted data and distorted decision-making.