Some languages, like SML, Haskell, and Scala, have built-in support for pattern matching, which is a generic way of branching based on the structure of data.
While not without its drawbacks, pattern matching can help eliminate a lot of boilerplate, and it's often cited as a reason why functional programming languages are so concise.
In this talk, John A. De Goes talks about the differences between built-in patterns, and so-called first-class patterns (which are "do-it-yourself" patterns implemented using other language features).
Unlike built-in patterns, first-class patterns aren't magical, so you can store them in variables and combine them in lots of interesting ways that aren't always possible with built-in patterns. In addition, almost every programming language can support first-class patterns (albeit with differing levels of effort and type-safety).
During the talk, you'll watch as a mini-pattern matching library is developed, and have the opportunity to follow along and build your own pattern matching library in the language of your choice.