Well, a primer is simply a sequence of nucleotides that are already attached onto that DNA template. And what that primer has is a free three prime hydroxyl group that can basically create that first phosphodia ester bond. And we'll see exactly how that looks like in just a moment. So there are three things that DNA polymerase needs. It needs the building blocks, the deoxy nucleuside, triphosphate molecules, and we have four different types. It actually needs that blueprint and that's the template DNA strand that exists in that double helical structure of DNA found inside our nuclei, C. It also needs a primer because the primer must exist for us to extend and build that phosphodiaester bond as we'll see in just a moment.