The Mercator projection is one of the most, if not the most, used projection for creating the maps. It has to be said though, that this projection is by any means not an accurate projection in the general picture.
The problem with the Mercator projection is that it shows the Equatorial parts accurately, but as the places get further away from it the distortion is becoming bigger and bigger. So in this projection it is easy to see that it is accurate at the low latitudes, but it is very inaccurate in the big latitudes.
This projection has this problem as it is not designed in a manner that allows it to cope with the situations where the scale is increasing and reaches a point of infinity.