diff --git a/bot/mcbot.go b/bot/mcbot.go
index 93a1638..38eb67d 100644
--- a/bot/mcbot.go
+++ b/bot/mcbot.go
@@ -12,8 +12,8 @@ import (
 	pk "github.com/Tnze/go-mc/net/packet"
 )
 
-// ProtocalVersion , the protocal version number of minecraft net protocal
-const ProtocalVersion = 480
+// ProtocolVersion , the protocol version number of minecraft net protocol
+const ProtocolVersion = 480
 
 // PingAndList chack server status and list online player.
 // Returns a JSON data with server status, and the delay.
@@ -30,7 +30,7 @@ func PingAndList(addr string, port int) ([]byte, time.Duration, error) {
 		//Handshake Packet
 		pk.Marshal(
 			0x00,                       //Handshake packet ID
-			pk.VarInt(ProtocalVersion), //Protocal version
+			pk.VarInt(ProtocolVersion), //Protocol version
 			pk.String(addr),            //Server's address
 			pk.UnsignedShort(port),
 			pk.Byte(1),
@@ -94,7 +94,7 @@ func (c *Client) JoinServer(addr string, port int) (err error) {
 		//Handshake Packet
 		pk.Marshal(
 			0x00,                       //Handshake packet ID
-			pk.VarInt(ProtocalVersion), //Protocal version
+			pk.VarInt(ProtocolVersion), //Protocol version
 			pk.String(addr),            //Server's address
 			pk.UnsignedShort(port),
 			pk.Byte(2),
diff --git a/nbt/read.go b/nbt/read.go
index 48fc53e..2a5e953 100644
--- a/nbt/read.go
+++ b/nbt/read.go
@@ -303,7 +303,7 @@ func (d *Decoder) readTag() (tagType byte, tagName string, err error) {
 
 func (d *Decoder) readNByte(n int) (buf []byte, err error) {
 	buf = make([]byte, n)
-	_, err = d.r.Read(buf) //what happend if (returned n) != (argument n) ?
+	_, err = d.r.Read(buf) //what happened if (returned n) != (argument n) ?
 	return
 }
 
diff --git a/net/packet/types.go b/net/packet/types.go
index 7d2f2d1..86cb201 100644
--- a/net/packet/types.go
+++ b/net/packet/types.go
@@ -6,15 +6,18 @@ import (
 	"math"
 )
 
+// A Field is both FieldEncoder and FieldDecoder
 type Field interface {
 	FieldEncoder
 	FieldDecoder
 }
 
+// A FieldEncoder can be encode as minecraft protocal used.
 type FieldEncoder interface {
 	Encode() []byte
 }
 
+// A FieldDecoder can Decode from minecraft protocal
 type FieldDecoder interface {
 	Decode(r DecodeReader) error
 }