How can geographic coordinate system such as WGS84 draw on screen?

Question

A Geographic Coordinate System represents coordinates on a sphere or ellipsoid.

To draw these coordinates on the screen does GIS software apply a default projection method, or does it just consider the lat/long coordinates as planar?

Answer 1

The latitude and longitude coordinates are just treated as planar coordinates.

Many GIS professionals refer to this colloquially as "unprojected". Some insist that any transformation from spherical to planar coordinates is a projection, this just happens to be an exceedingly simple one.