diff --git a/bot/client.go b/bot/client.go
index 80a459d..a5983c3 100644
--- a/bot/client.go
+++ b/bot/client.go
@@ -5,7 +5,7 @@ import (
 	"github.com/Tnze/go-mc/net"
 )
 
-// Client is the Object used to access Minecraft server
+// Client is used to access Minecraft server
 type Client struct {
 	conn *net.Conn
 	Auth
@@ -19,7 +19,13 @@ type Client struct {
 	Events eventBroker
 }
 
-//NewClient init and return a new Client
+// NewClient init and return a new Client.
+//
+// A new Client has default name "Steve" and zero UUID.
+// It is useable for an offline-mode game.
+//
+// For online-mode, you need login your Mojang account
+// and load your Name, UUID and AccessToken to client.
 func NewClient() (c *Client) {
 	c = new(Client)
 
diff --git a/bot/example_test.go b/bot/example_test.go
new file mode 100644
index 0000000..09ae12e
--- /dev/null
+++ b/bot/example_test.go
@@ -0,0 +1,71 @@
+package bot
+
+import (
+	"github.com/Tnze/go-mc/authenticate"
+	"log"
+)
+
+func ExamplePingAndList() {
+	resp, delay, err := PingAndList("localhost", 25565)
+	if err != nil {
+		log.Fatalf("ping and list server fail: %v", err)
+	}
+
+	log.Println("Status:", string(resp))
+	log.Println("Delay:", delay)
+}
+
+func ExampleClient_JoinServer_offline() {
+	c := NewClient()
+	c.Name = "Tnze" // set it's name before login.
+
+	//Login
+	err := c.JoinServer("localhost", 25565)
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Println("Login success")
+
+	// Regist event handlers
+	// 	c.Events.GameStart = onGameStartFunc
+	// 	c.Events.ChatMsg = onChatMsgFunc
+	// 	c.Events.Disconnect = onDisconnectFunc
+	//	...
+
+	//JoinGame
+	err = c.HandleGame()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
+
+func ExampleClient_JoinServer_online() {
+	c := NewClient()
+
+	//Login Mojang account to get AccessToken
+	auth, err := authenticate.Authenticate("Your E-mail", "Your Password")
+	if err != nil {
+		panic(err)
+	}
+	c.Name = auth.SelectedProfile.Name
+	c.AsTk = auth.SelectedProfile.ID
+
+	//Connect server
+	err = c.JoinServer("localhost", 25565)
+	if err != nil {
+		log.Fatal(err)
+	}
+	log.Println("Login success")
+
+	// Regist event handlers
+	// 	c.Events.GameStart = onGameStartFunc
+	// 	c.Events.ChatMsg = onChatMsgFunc
+	// 	c.Events.Disconnect = onDisconnectFunc
+	//	...
+
+	//Join the game
+	err = c.HandleGame()
+	if err != nil {
+		log.Fatal(err)
+	}
+}
diff --git a/bot/mcbot.go b/bot/mcbot.go
index 5700a25..0b690a1 100644
--- a/bot/mcbot.go
+++ b/bot/mcbot.go
@@ -1,3 +1,7 @@
+// Package bot implements a simple Minecraft client that can join a server
+// or just ping it for getting information.
+//
+// Runable example could be found at cmd/ .
 package bot
 
 import (
@@ -8,13 +12,13 @@ import (
 	pk "github.com/Tnze/go-mc/net/packet"
 )
 
-//ProtocalVersion is the protocal version
-// 477 for 1.14
+// ProtocalVersion , the protocal version number of minecraft net protocal
 const ProtocalVersion = 477
 
-// PingAndList chack server status and list online player
-// Return a JSON string about server status.
-// see JSON format at https://wiki.vg/Server_List_Ping#Response
+// PingAndList chack server status and list online player.
+// Returns a JSON data with server status, and the delay.
+//
+// For more infomation for JSON format, see https://wiki.vg/Server_List_Ping#Response
 func PingAndList(addr string, port int) ([]byte, time.Duration, error) {
 	conn, err := net.DialMC(fmt.Sprintf("%s:%d", addr, port))
 	if err != nil {
@@ -54,8 +58,8 @@ func PingAndList(addr string, port int) ([]byte, time.Duration, error) {
 	}
 
 	//PING
-	now := time.Now()
-	err = conn.WritePacket(pk.Marshal(0x01, pk.Long(now.Unix())))
+	startTime := time.Now()
+	err = conn.WritePacket(pk.Marshal(0x01, pk.Long(startTime.Unix())))
 	if err != nil {
 		return nil, 0, fmt.Errorf("bot: send ping packect fail: %v", err)
 	}
@@ -69,11 +73,11 @@ func PingAndList(addr string, port int) ([]byte, time.Duration, error) {
 	if err != nil {
 		return nil, 0, fmt.Errorf("bot: scan pong packect fail: %v", err)
 	}
-	if t != pk.Long(now.Unix()) {
+	if t != pk.Long(startTime.Unix()) {
 		return nil, 0, fmt.Errorf("bot: pong packect no match: %v", err)
 	}
 
-	return []byte(s), time.Now().Sub(now), err
+	return []byte(s), time.Since(startTime), err
 }
 
 // JoinServer connect a Minecraft server for playing the game.
diff --git a/bot/settings.go b/bot/settings.go
index 73af757..91cb4d7 100644
--- a/bot/settings.go
+++ b/bot/settings.go
@@ -27,7 +27,7 @@ const (
 
 //DefaultSettings are the default settings of client
 var DefaultSettings = Settings{
-	Locale:             "zh_CN",
+	Locale:             "zh_CN", // ^_^
 	ViewDistance:       15,
 	ChatMode:           0,
 	DisplayedSkinParts: Jacket | LeftSleeve | RightSleeve | LeftPantsLeg | RightPantsLeg | Hat,
diff --git a/cmd/daze/daze.go b/cmd/daze/daze.go
index 352dd30..f7aa949 100644
--- a/cmd/daze/daze.go
+++ b/cmd/daze/daze.go
@@ -12,11 +12,11 @@ func main() {
 	// For online-mode, you need login your Mojang account
 	// and load your Name and UUID to client:
 	//
-	// 		auth, err := authenticate.Authenticate(Your E-mail", "Your Password")
-	// 		if err != nil {
-	// 			panic(err)
-	// 		}
-	// 		c.Name, c.AsTk = auth.SelectedProfile.Name, auth.SelectedProfile.ID
+	// 	auth, err := authenticate.Authenticate(Your E-mail", "Your Password")
+	// 	if err != nil {
+	// 		panic(err)
+	// 	}
+	// 	c.Name, c.AsTk = auth.SelectedProfile.Name, auth.SelectedProfile.ID
 
 	//Login
 	err := c.JoinServer("localhost", 25565)
diff --git a/net/conn.go b/net/conn.go
index c3f4210..c3b9cd4 100644
--- a/net/conn.go
+++ b/net/conn.go
@@ -1,3 +1,4 @@
+// Package net pack network connection for Minecraft.
 package net
 
 import (
@@ -17,6 +18,7 @@ type Conn struct {
 	threshold int
 }
 
+// DialMC create a Minecraft connection
 func DialMC(addr string) (conn *Conn, err error) {
 	conn = new(Conn)
 	conn.socket, err = net.Dial("tcp", addr)
@@ -30,6 +32,7 @@ func DialMC(addr string) (conn *Conn, err error) {
 	return
 }
 
+// ReadPacket read a Packet from Conn.
 func (c *Conn) ReadPacket() (pk.Packet, error) {
 	p, err := pk.RecvPacket(c.ByteReader, c.threshold > 0)
 	if err != nil {
@@ -38,11 +41,13 @@ func (c *Conn) ReadPacket() (pk.Packet, error) {
 	return *p, err
 }
 
+//WritePacket write a Packet to Conn.
 func (c *Conn) WritePacket(p pk.Packet) error {
 	_, err := c.Write(p.Pack(c.threshold))
 	return err
 }
 
+// SetCipher load the decode/encode stream to this Conn
 func (c *Conn) SetCipher(encoStream, decoStream cipher.Stream) {
 	//加密连接
 	c.ByteReader = bufio.NewReader(cipher.StreamReader{ //Set reciver for AES
@@ -55,6 +60,9 @@ func (c *Conn) SetCipher(encoStream, decoStream cipher.Stream) {
 	}
 }
 
+// SetThreshold set threshold to Conn.
+// The data packet with length longger then threshold
+// will be compress when sendding.
 func (c *Conn) SetThreshold(t int) {
 	c.threshold = t
 }
diff --git a/net/packet/packet_test.go b/net/packet/packet_test.go
index 8fe7a7d..e11c89e 100644
--- a/net/packet/packet_test.go
+++ b/net/packet/packet_test.go
@@ -40,7 +40,7 @@ func TestUnpackInt(t *testing.T) {
 }
 
 func TestPositionPack(t *testing.T) {
-	// x (-33554432 to 33554431), y (-2048 to 2047), z (-33554432 to 33554431)
+	// This test is not good.
 
 	for x := -33554432; x < 33554432; x += 55443 {
 		for y := -2048; y < 2048; y += 48 {