The Adams-Onis Treaty was an agreement made between two countries, the United States and Spain, back in 1819. They came together to figure out the borders between the two countries because there were some disagreements about where they should be.
To make things simpler, they decided that the US would get ownership of Florida while Spain would keep control over Texas. The treaty also made clear what areas belonged to each country in the western part of North America.
Overall, the treaty was meant to bring clarity and peace between the two countries about where their borders were and to prevent any future disagreements. It was an important agreement because it helped to establish the borders of the United States we know today.