Lost in France is a non-profit organization. Because of this, we need to find other ways to get enough money to keep the website and other services running. This is why Lost in France has banner adverts on most of its pages. It's not to make profit, it's just to make sure that you can keep coming to the website to learn French!
Adverts are also present on the videos, but you can stop seeing them by clicking the small X in the top right corner of the ad.