This question is asked practically every day on C# Forums: "how do I get a value from Form1 to Form2?" or the other way around. There is a shocking amount of bad advice out there on the internet about how to go about doing this. This tutorial is intended to show you more "correct" ways of passing data between forms.
The scope of this tutorial is limited to passing data between forms. We will look at both properties and custom events, but in a brief overview.