In the introduction, the author tries to define HFT using the voices of leading HFT players. What are the characteristics of HFT? There is no agreement on a common definition of HFT, but there are some elements that one can at least attribute to HFT. They are
Low latency trading.
High turnover strategy.
Trader goes home `flat' with no open position.
The goal of any HFT firm broadly is to have a set of uncorrrelated trading strategies that has statistically more winners than losers for all the trading positions of the day.