diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..6ed48a9
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+.env
+node_modules
diff --git a/IO.cjs b/IO.cjs
new file mode 100644
index 0000000..3d3d893
--- /dev/null
+++ b/IO.cjs
@@ -0,0 +1,10 @@
+const fs = require("fs");
+
+console.log("Start");
+
+fs.readFile("test.txt", "utf8", (err, data) => {
+  if (err) throw err;
+  console.log("File:", data.trim());
+});
+
+console.log("End");
\ No newline at end of file
diff --git a/eventLoop.js b/eventLoop.js
new file mode 100644
index 0000000..42ebce7
--- /dev/null
+++ b/eventLoop.js
@@ -0,0 +1,7 @@
+console.log("A");
+
+setTimeout(() => {
+  console.log("B");
+}, 0);
+
+console.log("C");
diff --git a/test.txt b/test.txt
new file mode 100644
index 0000000..693cf43
--- /dev/null
+++ b/test.txt
@@ -0,0 +1 @@
+"Hello World!"
\ No newline at end of file
diff --git a/type.ts b/type.ts
new file mode 100644
index 0000000..bc9b7f4
--- /dev/null
+++ b/type.ts
@@ -0,0 +1,48 @@
+let a: string = "UMC 10th";
+
+let b: {
+  id: number;
+  name: string;
+} = {
+  id: 1,
+  name: "홍길동",
+};
+
+let f: null[] = [null, null, null];
+let g: undefined[] = [undefined, undefined, undefined];
+
+let h: string | number;
+h = "UMC";
+h = 1;
+
+// function 형태
+function test1(value: number): number {
+  return value;
+}
+
+// arrow function 형태
+const test2 = (value: number): number => {
+  return value;
+};
+
+function getFirst<T>(arr: T[]): T {
+  return arr[0];
+}
+
+const i = getFirst([1, 2, 3]); // i는 number
+const j = getFirst(["U", "M", "C"]); // j는 string
+
+type ChallengerType = {
+  id: number;
+  name: string;
+};
+
+interface Challenger {
+  id: number;
+  name: string;
+}
+
+const me: Challenger = {
+  id: 1,
+  name: "홍길동",
+};
\ No newline at end of file