Go's source code (comment actually) says it all tbh: https://github.com/golang/go/blob/master/src/io/io.go#L55 https://github.com/golang/go/blob/master/src/io/i

Go's source code (comment actually) says it all tbh: https://github.com/golang/go/blob/master/src/io/io.go#L55 https://github.com/golang/go/blob/master/src/io/io.go#L55 (very much) tldr: anything that implements `Read(p []byte) (n int, err error)` - is a Reader.