diff --git a/src/net/net.go b/src/net/net.go
index 6198d94a14d..b9a78266b56 100644
--- a/src/net/net.go
+++ b/src/net/net.go
@@ -102,9 +102,13 @@ func init() {
 }
 
 // Addr represents a network end point address.
+//
+// The two methods Network and String conventionally return strings
+// that can be passed as the arguments to Dial, but the exact form
+// and meaning of the strings is up to the implementation.
 type Addr interface {
-	Network() string // name of the network
-	String() string  // string form of address
+	Network() string // name of the network (for example, "tcp", "udp")
+	String() string  // string form of address (for example, "127.0.0.1:25", "[2001:db8::1]:80")
 }
 
 // Conn is a generic stream-oriented network connection.