diff --git a/hacking-go/learn04/defer/defer.go b/hacking-go/learn04/defer/defer.go
new file mode 100644
index 0000000..d6599ca
--- /dev/null
+++ b/hacking-go/learn04/defer/defer.go
@@ -0,0 +1,14 @@
+
+package main
+
+import "fmt"
+
+func main() {
+    // This line will be executed immediately.
+    defer fmt.Println("This runs after main")
+    
+    // This line will be executed immediately.
+    fmt.Println("Main ended")
+    // After the surrounding function returns, 
+    // the deferred function will execute.
+}
diff --git a/hacking-go/learn04/defer/defer1.go b/hacking-go/learn04/defer/defer1.go
new file mode 100644
index 0000000..1fcc59d
--- /dev/null
+++ b/hacking-go/learn04/defer/defer1.go
@@ -0,0 +1,40 @@
+package main
+
+import "fmt"
+
+func defer1_advance() {
+	num := 100
+
+	// First deferred function capturing the value of num at this point
+	defer func(n int) {
+		fmt.Println("Deferred 1: After main returns", n) // This will print "Deferred 1: After main returns 110" after main() returns.
+	}(num)
+
+	num++ // num is incremented to 101
+
+	// Second deferred function capturing the updated value of num after the first increment
+	defer func(n int) {
+		fmt.Println("Deferred 2: After main returns", n) // This will print "Deferred 2: After main returns 101" after main() returns.
+	}(num)
+
+	num += 9 // num is now 110
+
+	fmt.Println("Inside main", num) // Prints "Inside main 110"
+}
+
+func defer1() {
+
+	num := 100
+	defer fmt.Println("After main returns", num)
+
+	num++
+	num += 9
+	fmt.Println("Inside main", num)
+
+}
+
+func main() {
+	defer1()
+	defer1_advance()
+
+}
diff --git a/hacking-go/learn04/defer/defer2.go b/hacking-go/learn04/defer/defer2.go
new file mode 100644
index 0000000..6b89eb0
--- /dev/null
+++ b/hacking-go/learn04/defer/defer2.go
@@ -0,0 +1,59 @@
+package main
+
+import (
+	"fmt"
+	"os"
+)
+
+func openfile() {
+	// Open a file
+	file, err := os.Open("tainguyenbp.txt")
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+
+	// Defer the closing of the file
+	defer file.Close()
+
+	// Perform operations on the file
+	// For demonstration, let's just print its contents
+	fmt.Println("File contents:")
+	data := make([]byte, 100)
+	count, err := file.Read(data)
+	if err != nil {
+		fmt.Println("Error reading file:", err)
+		return
+	}
+	fmt.Println(string(data[:count]))
+}
+
+func openfileno() {
+	// Open a file
+	file, err := os.Open("tainguyenbp1.txt")
+	if err != nil {
+		fmt.Println("Error:", err)
+		return
+	}
+
+	// Defer the closing of the file
+	defer file.Close()
+
+	// Perform operations on the file
+	// For demonstration, let's just print its contents
+	fmt.Println("File contents:")
+	data := make([]byte, 100)
+	count, err := file.Read(data)
+	if err != nil {
+		fmt.Println("Error reading file:", err)
+		return
+	}
+	fmt.Println(string(data[:count]))
+}
+
+func main() {
+
+	openfile()
+	openfileno()
+	// Any other operations on the file can go here
+}
diff --git a/hacking-go/learn04/defer/readme.md b/hacking-go/learn04/defer/readme.md
new file mode 100644
index 0000000..4bd4a8e
--- /dev/null
+++ b/hacking-go/learn04/defer/readme.md
@@ -0,0 +1 @@
+defer
diff --git a/hacking-go/learn04/defer/tainguyenbp.txt b/hacking-go/learn04/defer/tainguyenbp.txt
new file mode 100644
index 0000000..9daeafb
--- /dev/null
+++ b/hacking-go/learn04/defer/tainguyenbp.txt
@@ -0,0 +1 @@
+test
diff --git a/hacking-go/learn04/defer/tainguyenbp1.txt b/hacking-go/learn04/defer/tainguyenbp1.txt
new file mode 100644
index 0000000..e69de29