What does a Thumper actually do?

[Tenkillsmore]

Hello, I did search this but with 15345 posts that has thumper in it I gave up. I have one but have not used it yet. I read that a thumper imparts more flavor to the product by passing the vapour thru a liquid of whatever flavor you are going for. I can see how this would work, but doesn't that cool the vapour down to liquid? Then I read that you can increase the ABV by using a thumper, this I don't understand how it would work, if true could some one explain it? What is the correct result from a thumper's use? Thanks.