For three main reasons. The first one is to meet new people and talk to them to see their different point of views of a lot of topics that will make me see the world differently. The second reason is that I think the best way to travel a country through their locals, they know their country well, so I can get the most out of my trip. Finally, to save money by being with a local.

I can share with my host the experience that I gain through the countries that I visited. We can plan a trip together and wonder in his/her country together. Most importantly, friendship, I think the best thing I can do is share a bond with my host :)