As children we first learn about the notion of weightlessness in outer space and the idea of zero gravity, but these concepts are actually a bit more nuanced than may appear. For example, why satellites orbit Earth instead of crashing into it because of Earth’s gravitational pull can be a mystery if you have never studied physics. The following TED Education animation does a good job of illustrating the basic principle behind orbiting objects without going into too many details.
If you’ve been exposed to high school physics, the Wikipedia article on weightlessness is uncharacteristically clear on some of the more advanced aspects of the subject. In particular, you may be surprised to learn that Einstein in developing his theory of relativity realized that gravitational interaction cannot be felt when all other forces are removed and this led him to consider the possibility that gravity is the result of the curvature of space. If you’re interested in the details of relativity and a modern interpretation of Newtonian mechanics, Leonard Susskind’s set of physics lectures is the best place to start.