Like other LCD imaging technologies, IPS is named after the behavior of the liquid crystals inside the subpixels. In the case of IPS, the subpixels don't let through any light when they are idle. The crystals are arranged on a plane, and light transmission is ensured by rotating them (hence the name In-Plane Switching). This approach brings a number of advantages compared with other LCD display technologies.
The first advantage is the previously mentioned wide viewing angle, meaning the monitor can be viewed from all sides with little or no change in colour. Compared with the older TN technology, you can look forward to much better contrast. This is mainly due to the more realistic reproduction of black. Conversely, a slight disadvantage is the higher cost of production and resulting higher price tag.