Gene mapping is the process that involves finding the positions of genes on chromosomes and also determining what the distance is between the genes on a given chromosome. Now, typically in genetics and biology we express the distance between any two genes on a given chromosome by using special units known as Map units or recombination units. So these two terms are basically used interchangeably. They mean the same exact thing. Now, as we'll see in just a moment, to actually calculate the Map units the distance between our two genes and Map units we have to calculate the percent recombination between those two genes. So to see exactly what we mean by that, let's take a look at the following example.