When black holes merge or other energetic cosmic events perturb spacetime, the gravitational waves they produce act as a complicated signal that encodes information about the source (like its mass, spin, and location). If we understand the signal well, we can pick out this information. Here, we'll learn how different sources produce different gravitational-wave signals, and we'll see how those signals vary with the parameters that describe the source (masses, spins, orientation, etc).