Quick thermal paste question

Hey guys, n00b here.
I wasn't exactly sure where to ask this question but since it pertains to the CPU I'd figure I ask here.

So Im about to build my first PC and I have all the parts. However, Im curious as to if I need to purchase thermal paste for my CPU. I've watched tutorials of PC building and it seems like there is preapplied thermal paste that comes with the stock CPU cooler/fan.

So just to be sure, do I need to purchase and apply thermal paste or is this paste already on the CPU cooler?

Thanks!