Go basic anonymous variable

go Anonymous variables are often used in ,go What are anonymous variables in , What's the usage? ？

Code ：

package main

import "fmt"

func GetData() (int, int) {
	return 100, 200
}
func main(){
	a, _ := GetData()
	_, b := GetData()
	//c := GetData()	//  Report errors ：assignment mismatch: 1 variable but GetData returns 2 values
	fmt.Println(a, b)
}

Running results ：