diff --git a/examples/frameworkServer/main.go b/examples/frameworkServer/main.go
index f359e09..246e36e 100644
--- a/examples/frameworkServer/main.go
+++ b/examples/frameworkServer/main.go
@@ -20,7 +20,6 @@ type MyServer struct {
 	playerList *server.PlayerList
 }
 
-const ServerName = "MyServer"
 const MaxPlayer = 20
 const IconPath = "./server-icon.png"
 
@@ -28,7 +27,7 @@ var motd = chat.Message{Text: "A Minecraft Server ", Extra: []chat.Message{{Text
 
 func main() {
 	playerList := server.NewPlayerList(MaxPlayer)
-	serverInfo, err := server.NewPingInfo(playerList, ServerName, server.ProtocolVersion, motd, readIcon())
+	serverInfo, err := server.NewPingInfo(playerList, server.ProtocolName, server.ProtocolVersion, motd, readIcon())
 	if err != nil {
 		log.Fatalf("Set server info error: %v", err)
 	}
diff --git a/save/chunk_test.go b/save/chunk_test.go
index 5d5a186..386dac8 100644
--- a/save/chunk_test.go
+++ b/save/chunk_test.go
@@ -27,7 +27,7 @@ func TestColumn(t *testing.T) {
 }
 
 func BenchmarkColumn_Load(b *testing.B) {
-	// Test how many time we load a chunk
+	// Test how many times we load a chunk
 	var c Column
 	r, err := region.Open("testdata/region/r.-1.-1.mca")
 	if err != nil {
diff --git a/save/palette.go b/save/palette.go
index 8be70db..8106e7e 100644
--- a/save/palette.go
+++ b/save/palette.go
@@ -13,8 +13,8 @@ type BlockState interface {
 type palette interface {
 	id(v BlockState) int
 	value(i int) BlockState
-	io.ReaderFrom
-	io.WriterTo
+	pk.FieldEncoder
+	pk.FieldDecoder
 	read(r nbt.DecoderReader) (int, error)
 }
 
diff --git a/server/auth/auth.go b/server/auth/auth.go
index 0f495c3..311e1b7 100644
--- a/server/auth/auth.go
+++ b/server/auth/auth.go
@@ -59,7 +59,7 @@ func Encrypt(conn *net.Conn, name string) (*Resp, error) {
 		return nil, err
 	}
 
-	//confirm the verify token
+	//confirm to verify token
 	if !bytes.Equal(VT1, VT2) {
 		return nil, errors.New("verify token not match")
 	}
diff --git a/server/gameplay.go b/server/gameplay.go
index 4cfe553..efccff1 100644
--- a/server/gameplay.go
+++ b/server/gameplay.go
@@ -6,5 +6,9 @@ import (
 )
 
 type GamePlay interface {
+	// AcceptPlayer handle everything after "LoginSuccess" is sent.
+	//
+	// Note: the connection will be closed after this function returned.
+	// You don't need to close the connection, but to keep not returning while the player is playing.
 	AcceptPlayer(name string, id uuid.UUID, protocol int32, conn *net.Conn)
 }
diff --git a/server/login.go b/server/login.go
index 18b472d..5defdb1 100644
--- a/server/login.go
+++ b/server/login.go
@@ -3,23 +3,49 @@ package server
 import (
 	"fmt"
 
+	"github.com/google/uuid"
+
+	"github.com/Tnze/go-mc/chat"
 	"github.com/Tnze/go-mc/data/packetid"
 	"github.com/Tnze/go-mc/net"
 	pk "github.com/Tnze/go-mc/net/packet"
 	"github.com/Tnze/go-mc/offline"
 	"github.com/Tnze/go-mc/server/auth"
-	"github.com/google/uuid"
 )
 
+// LoginHandler is used to handle player login process, that is,
+// from clientbound "LoginStart" packet to serverbound "LoginSuccess" packet.
 type LoginHandler interface {
 	AcceptLogin(conn *net.Conn, protocol int32) (name string, id uuid.UUID, err error)
 }
 
-type MojangLoginHandler struct {
-	OnlineMode bool
-	Threshold  int
+// LoginChecker is the interface to check if a player is allowed to log in the server.
+// The checking could be anything, server player number, blacklist or whitelist.
+// If a player is not allowed to, the reason should be returned and will be sent to client by "LoginDisconnect" packet.
+type LoginChecker interface {
+	CheckPlayer(name string, id uuid.UUID) (ok bool, reason chat.Message)
 }
 
+// MojangLoginHandler is a standard LoginHandler that implement both online and offline login progress.
+// This implementation also support custom LoginChecker.
+// None of Custom login packet (also called LoginPluginRequest/Response) is support by this implementation.
+// To do that, implement your own LoginHandler imitate this code.
+type MojangLoginHandler struct {
+	// OnlineMode enables to check player's account.
+	// And also encrypt the connection after login.
+	OnlineMode bool
+
+	// Threshold set the smallest size of raw network payload to compress.
+	// Set to 0 to compress all packets. Set to -1 to disable compression.
+	Threshold int
+
+	// LoginChecker is used to apply some checks before sending "LoginSuccess" packet
+	// (e.g. blacklist or is server full).
+	// This is optional field and can be set to nil.
+	LoginChecker
+}
+
+// AcceptLogin implement LoginHandler for MojangLoginHandler
 func (d *MojangLoginHandler) AcceptLogin(conn *net.Conn, protocol int32) (name string, id uuid.UUID, err error) {
 	//login start
 	var p pk.Packet
@@ -55,7 +81,8 @@ func (d *MojangLoginHandler) AcceptLogin(conn *net.Conn, protocol int32) (name s
 	//set compression
 	if d.Threshold >= 0 {
 		err = conn.WritePacket(pk.Marshal(
-			packetid.SetCompression, pk.VarInt(d.Threshold),
+			packetid.SetCompression,
+			pk.VarInt(d.Threshold),
 		))
 		if err != nil {
 			return
@@ -63,8 +90,25 @@ func (d *MojangLoginHandler) AcceptLogin(conn *net.Conn, protocol int32) (name s
 		conn.SetThreshold(d.Threshold)
 	}
 
+	// check if player can join (whitelist, blacklist, server full or something else)
+	if d.LoginChecker != nil {
+		if ok, result := d.CheckPlayer(name, id); !ok {
+			// player is not allowed to join the server
+			err = conn.WritePacket(pk.Marshal(
+				packetid.LoginDisconnect,
+				result,
+			))
+			if err != nil {
+				return
+			}
+			err = loginFailErr{reason: result}
+			return
+		}
+	}
+
 	// send login success
-	err = conn.WritePacket(pk.Marshal(packetid.LoginSuccess,
+	err = conn.WritePacket(pk.Marshal(
+		packetid.LoginSuccess,
 		pk.UUID(id),
 		pk.String(name),
 	))
@@ -78,3 +122,11 @@ type wrongPacketErr struct {
 func (w wrongPacketErr) Error() string {
 	return fmt.Sprintf("wrong packet id: expect %#02X, get %#02X", w.expect, w.get)
 }
+
+type loginFailErr struct {
+	reason chat.Message
+}
+
+func (l loginFailErr) Error() string {
+	return "login error: " + l.reason.ClearString()
+}
diff --git a/server/ping.go b/server/ping.go
index ce23fa2..6ca8e6f 100644
--- a/server/ping.go
+++ b/server/ping.go
@@ -14,14 +14,24 @@ import (
 	"strings"
 )
 
+// ListPingHandler collect server running status info
+// which is used to handle client ping and list progress.
 type ListPingHandler interface {
+	// Name of the server version
 	Name() string
+	// Protocol number
 	Protocol() int
 	MaxPlayer() int
 	OnlinePlayer() int
+	// PlayerSamples is a short list of some player in the server
 	PlayerSamples() []PlayerSample
 
 	Description() *chat.Message
+	// FavIcon should be a PNG image that is Base64 encoded
+	// (without newlines: \n, new lines no longer work since 1.13)
+	// and prepended with "data:image/png;base64,".
+	//
+	// This method can return empty string if no icon is set.
 	FavIcon() string
 }
 
diff --git a/server/ping_test.go b/server/ping_test.go
deleted file mode 100644
index fc9c2ba..0000000
--- a/server/ping_test.go
+++ /dev/null
@@ -1,36 +0,0 @@
-package server
-
-import (
-	"github.com/Tnze/go-mc/chat"
-	"image"
-	"os"
-)
-
-func ExamplePingInfo_standardUsage() {
-	// Read server icon
-	f, err := os.Open("./server-icon.png")
-	if err != nil {
-		panic(err)
-	}
-	defer f.Close()
-	icon, _, err := image.Decode(f)
-	if err != nil {
-		panic(err)
-	}
-	// Set server info
-	playerList := NewPlayerList(20)
-	pingInfo, err := NewPingInfo(playerList, "1.18", 757, chat.Text("A Minecraft Server"), icon)
-	if err != nil {
-		panic(err)
-	}
-	// Start listening
-	s := Server{
-		ListPingHandler: pingInfo,
-		LoginHandler:    nil,
-		GamePlay:        nil,
-	}
-	err = s.Listen("0.0.0.0:25565")
-	if err != nil {
-		return
-	}
-}
diff --git a/server/server.go b/server/server.go
index 639f47d..2418663 100644
--- a/server/server.go
+++ b/server/server.go
@@ -2,16 +2,16 @@
 // You can build the server you want by combining the various functional modules provided here.
 // An example can be found in examples/frameworkServer.
 //
-// A server is roughly divided into two parts:
+// A server is roughly divided into two parts: Gate and GamePlay
 //
 //	+-----------------------------------------------------------------+
 //	|                     Go-MC Server Framework                      |
 //	+--------------------------------------+--------------------------+
 //	|               Gate                   |         GamePlay         |
 //	+--------------------+-----------------+                          |
-// 	|    LoginHandler    | ListPingHandler |                          |
-// 	+--------------------+--------+--------+-----------+--------------+
-// 	| MojangLoginHandler |  Info  |     PlayerList     |  Others....  |
+//	|    LoginHandler    | ListPingHandler |                          |
+//	+--------------------+--------+--------+-----------+--------------+
+//	| MojangLoginHandler |  Info  |     PlayerList     |  Others....  |
 //	+--------------------+--------+--------------------+--------------+
 //
 // Gate, which is used to respond to the client login request, provide login verification,
@@ -26,6 +26,7 @@ package server
 
 import "github.com/Tnze/go-mc/net"
 
+const ProtocolName = "1.18.1"
 const ProtocolVersion = 757
 
 type Server struct {