Automated software application that is capable of trading (buy/sell) crypto currencies on public exchanges, based on a predefined set of rules.
Trading bots rely on technical analysis and other trading factors, that are different from one bot to the next ... most bots offer the options to alter settings, chose strategies, set targets etc ...
Bots use API's to communicate with exchanges that they trade on, which makes them a popular target for hackers. Poorly coded bots can pose a serious security threat so use them at your own risk.
It's a fact that BOTs can trade very effectively in certain market conditions, especially during bullish periods, but the situation changes when the markets start to fall.