So before crossing over takes place, homologous pairs must find each other and move side by side with respect to each other. And this pairing, this movement of the homologous chromosomes next to one another, is known as synapses. And this is shown in the following diagram. So the first step of synapses is the following. These two homologous pairs of chromosomes that we spoke of earlier actually have to find each other and move side by side. And then when they move side by side, these chromatids of these two chromosomes have to overlap.