为什么通道参数的语法不同？ 有任何潜在的含义吗？

I'm digging around the use of channels in Go, and in this example from Tour of Go, we have this line:

func sum(s []int, c chan int) {

I'm familiar with the syntax: variableName type in Go. But what does this mean? c chan int

Is this a channel type, or an int type, or a chan int type? And what's with the weird syntax?

I cannot search for the answer, if this is a duplicate, kindly give me a link to the original post in the comment, and I'll delete the question.

I'm familiar with the syntax: variableName type in Go. Is this a channel type, or an int type, or a chan int type? And what's with the weird syntax?

chan int is the type. It's just as "weird" as []int.