Dependent upon the number of standard parallels. One line, indicated by the standard parallel. Two lines, specified as 1st and 2nd standard parallels. Local shapes are true along the standard parallels. Distortion is constant along any given parallel.
Distortion increases with distance from the standard parallels.
Distortion increases with distance from the standard parallels. True along the meridians and the standard parallels. Scale is constant along any given parallel, but changes from parallel to parallel. Range in latitude should be limited to 30 degrees. Common for atlas maps of small countries.