The mercator projection is the most common projection found on the internet and it’s the default map projection in Maproom. It’s been invented by Mercator at the end of the middle ages. The main benefit of this map projection is the fact that constant bearings result in straight lines on this map. This makes it very suitable for nautical navigation: draw a straight line from port to port, measure the bearing and sail away. A downside of the mercator projection is that the distortion of areas is pretty extreme. It’s been suggested this map is still popular because it favors Europe and North America over Africa and South America.

Wikipedia article