Go's interfaces — static, checked at compile time, dynamic when asked for — are, for me, the most exciting part of Go from a language design point of view. If I could export one feature of Go into other languages, it would be interfaces.

— Russ Cox

We'll cover the following topics:

• Taking advantage of Go's automatically satisfied interfaces
• Choosing third-party packages that are easy to extend for your own purposes
• How interfaces are used in Go's standard library
• A look at the internals.

There will be a mixture of practices I've seen used in third-party packages and the standard library, and also some I've successfully applied to our own large codebase.