A TN monitor uses a Twisted Nematic panel. This is known for a fast response time and a high refresh rate, so it's very suitable for a gaming monitor, especially for fast shooters and racing games. TN panels have a less good color rendering and a less wide viewing angle than VA and IPS panels, but they also cost less. If you're mainly concerned about speed, a TN panel is very suitable. A TN monitor is also great for internet, text processing, and emailing.