As a C# developer, there are obviously a lot of skills you need to master to be effective: language syntax, framework classes, third-party libraries, databases, regular expressions, the HTTP protocol, etc. But there are a handful of things that I consider to be really fundamental, and I often see C# developers, even experienced ones, who don't master them. So, I'm doing a series about those things! Today: hash codes. The GetHashCode method OK, I realize that most developers don't need to implement their own hash table, or even implement GetHashCode very often, but still, it's important to know about this.