Three way link Exchange is a method of exchanging links between three websites for e.g. if there are three websites A, B, C.
site A requested site B for link exchange in response to the request site B also requested site A to add link to site B. Now site A added link to site B but site B added Site A link to site C but not to site B.
So now Site B is having backlink on site A and site A is having a backlink on site C. this whole chain defines three way link exchange...which actually seems to be one way link exchange for site B and site A.... | 
What is 3 way linkbuilding? 
