What is high frequency trading? What are its risks, and its regulations?

Technology has deeply impacted finance, the last discoveries in terms of artificial intelligence have made new things possible. Today, a totally independent algorithm can learn new things by itself and take investment decisions in a record time. These artificial intelligences coupled with very fast internet connections allowed the creation of high frequency trading. High frequency trading suffers from a bad reputation, it has been accused of being responsible for crashes, for being risky and unfair. And if traders are generally considered as greedy, it is even worst for high frequency traders. But what is the reality? This thesis aims to fully present high frequency trading, its history, its specificities , the strategies it uses and its impact on financial markets. It also focuses on ways of regulating high frequency trading.