Terrain Mesh provides the sim with elevation information which describes the shape of the earth's surface. The more accurate the source data, the more
realistic the earth appears in the sim. The default mesh included with Flight Simulator improves with each version, but better code
efficiency allows us to add higher resolution mesh with little impact on frame rates. Much better in some areas.
While the use of such data is not very complicated, some additional knowledge can go a long way toward enriching your flying experience.
There is a lot of mesh, and a lot of information about mesh, available on the internet. Very little of this information is well organized,
and some of it is not entirely accurate, even conflicting. With this in mind, several key issues concerning mesh development and use
are discussed on this site. I hope this information will increase your enjoyment of the mesh available, and of your use of the sim in general.