When you complete any research, you get some "points" in that field. Those points are there as knowledge you have gained, and that you can trade.
There is no benefit stockpiling these points, they give you nothing, they are meant just as "coin" for diplomacy. When you trade these points with some othe faction, you get their knowledge, meaning your own research benefit from them and gets shorter.
I'm not sure how the points are distributed, I think that if you buy points in the field you're actively researching now, it shortens the time of your current research. Instead, if you buy points in fields you're not actively researching, they get randomly assigned to techs. That means I may have the Blacksmithing tech bar half filled after a trade, even if I never researched it, for example.
Trading these points is really beneficial for you, but mind to what faction you give them, they'll get benefits too. You don't want, for example, to give warfare points to a warfare-oriented faction that you suspect may attack you later.
Best way I found is to find a "tech-buddy", make a technology treat with them (so you both gain some % research per turn), and keep trading tech with them everytime you get some points.
Also note you can trade these points for other valuables, if you need them or it fits your playstyle (gold, horses, crystals, metal, etc)
