diff --git a/common/net/address.proto b/common/net/address.proto
index 4670b769e..07f106d0a 100644
--- a/common/net/address.proto
+++ b/common/net/address.proto
@@ -6,7 +6,7 @@ option go_package = "net";
 option java_package = "com.v2ray.core.common.net";
 option java_multiple_files = true;
 
-// Address of a network host. It may be an IP address or a domain address.
+// Address of a network host. It may be either an IP address or a domain address.
 message IPOrDomain {
   oneof address {
     // IP address. Must by either 4 or 16 bytes.
diff --git a/common/net/network.proto b/common/net/network.proto
index 19a75ad65..3915091c0 100644
--- a/common/net/network.proto
+++ b/common/net/network.proto
@@ -14,6 +14,7 @@ enum Network {
   UDP = 3;
 }
 
+// NetworkList is a list of Networks.
 message NetworkList {
   repeated Network network = 1;
 }
diff --git a/common/protocol/server_spec.proto b/common/protocol/server_spec.proto
index 55b6d4ca4..936140105 100644
--- a/common/protocol/server_spec.proto
+++ b/common/protocol/server_spec.proto
@@ -13,4 +13,4 @@ message ServerEndpoint {
   v2ray.core.common.net.IPOrDomain address = 1;
   uint32 port = 2;
   repeated v2ray.core.common.protocol.User user = 3;
-}
\ No newline at end of file
+}
diff --git a/common/protocol/user.proto b/common/protocol/user.proto
index 87fb729f1..b92574c7b 100644
--- a/common/protocol/user.proto
+++ b/common/protocol/user.proto
@@ -8,6 +8,7 @@ option java_multiple_files = true;
 
 import "v2ray.com/core/common/serial/typed_message.proto";
 
+// User is a generic user for all procotols.
 message User {
   uint32 level = 1;
   string email = 2;
diff --git a/common/serial/bytes.go b/common/serial/bytes.go
index fd832bbf0..abcf4f69a 100644
--- a/common/serial/bytes.go
+++ b/common/serial/bytes.go
@@ -9,10 +9,12 @@ func ByteToHexString(value byte) string {
 	return hex.EncodeToString([]byte{value})
 }
 
+// BytesToUint16 deserializes a byte array to an uint16 in big endian order. The byte array must have at least 2 elements.
 func BytesToUint16(value []byte) uint16 {
 	return uint16(value[0])<<8 | uint16(value[1])
 }
 
+// BytesToUint32 deserializes a byte array to an uint32 in big endian order. The byte array must have at least 4 elements.
 func BytesToUint32(value []byte) uint32 {
 	return uint32(value[0])<<24 |
 		uint32(value[1])<<16 |
@@ -20,6 +22,7 @@ func BytesToUint32(value []byte) uint32 {
 		uint32(value[3])
 }
 
+// BytesToInt64 deserializes a byte array to an int64 in big endian order. The byte array must have at least 8 elements.
 func BytesToInt64(value []byte) int64 {
 	return int64(value[0])<<56 |
 		int64(value[1])<<48 |
diff --git a/common/serial/hash.go b/common/serial/hash.go
deleted file mode 100644
index 63aa4c022..000000000
--- a/common/serial/hash.go
+++ /dev/null
@@ -1,10 +0,0 @@
-package serial
-
-import "hash"
-
-func WriteHash(h hash.Hash) func([]byte) (int, error) {
-	return func(b []byte) (int, error) {
-		h.Sum(b[:0])
-		return h.Size(), nil
-	}
-}
diff --git a/common/serial/numbers.go b/common/serial/numbers.go
index 05a98bbe1..54ebda723 100644
--- a/common/serial/numbers.go
+++ b/common/serial/numbers.go
@@ -2,6 +2,7 @@ package serial
 
 import "strconv"
 
+// Uint16ToBytes serializes an uint16 into bytes in big endian order.
 func Uint16ToBytes(value uint16, b []byte) []byte {
 	return append(b, byte(value>>8), byte(value))
 }
diff --git a/common/serial/string.go b/common/serial/string.go
index 6a7ea9181..490e49c95 100644
--- a/common/serial/string.go
+++ b/common/serial/string.go
@@ -5,6 +5,7 @@ import (
 	"strings"
 )
 
+// ToString serialize an abitrary value into string.
 func ToString(v interface{}) string {
 	if v == nil {
 		return " "