The highlands on the moon are areas of mountains and valleys, whereas the lowlands are dominated by mares, or areas of flat plains.
The highlands, also known as terrae, have been dated as forming 4.4 billion years ago, are the lighter-colored regions of the Moon.
The dark, featureless lunar plains which can clearly be seen with the naked eye are called maria, or mare for singular, and were once believed by ancient astronomers to be filled with water.
We now know that they are huge solidified pools of ancient basaltic lava.
Craters are found in both highlands and lowlands.
The side of the Moon we see from Earth is split 50/50 between the two terrains.
The dark side of the moon which we can’t see is almost all highland.