diff --git a/README.org b/README.org
index db0f386..1eb48a7 100644
--- a/README.org
+++ b/README.org
@@ -17,5 +17,6 @@ For faster compilation, compile glad;
 gcc -Ilibs/glad/include/ -c libs/glad/src/glad.c
 #+end_src
 * Terms
-VBO - vertex buffer objects
-VAO - vertex array object
+VBO - Vertex Buffer Objects
+VAO - Vertex Array Object
+EBO - Element Buffer Object
diff --git a/main.c b/main.c
index d5303e1..ca5bd24 100644
--- a/main.c
+++ b/main.c
@@ -110,17 +110,25 @@ int main(void) {
     glDeleteShader(fragmentShader);  
 
     float vertices[] = {
-        -0.5f, -0.5f, 0.0f,
-        0.5f, -0.5f, 0.0f,
-        0.0f,  0.5f, 0.0f
-    };  
+        0.5f,  0.5f, 0.0f,  // top right
+        0.5f, -0.5f, 0.0f,  // bottom right
+        -0.5f, -0.5f, 0.0f,  // bottom left
+        -0.5f,  0.5f, 0.0f   // top left 
+    };
+    unsigned int indices[] = {  // note that we start from 0!
+        0, 1, 3,   // first triangle
+        1, 2, 3    // second triangle
+    }; 
 
-    unsigned int VBO, VAO;
+    unsigned int VBO, VAO, EBO;
     glGenVertexArrays(1, &VAO); 
+    glGenBuffers(1, &EBO);
     glGenBuffers(1, &VBO); 
     glBindVertexArray(VAO);
     glBindBuffer(GL_ARRAY_BUFFER, VBO);
     glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+    glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+    glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW); 
     glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
     glEnableVertexAttribArray(0); 
 
@@ -136,7 +144,10 @@ int main(void) {
 
         glUseProgram(shaderProgram);
         glBindVertexArray(VAO);
-        glDrawArrays(GL_TRIANGLES, 0, 3);
+        // glDrawArrays(GL_TRIANGLES, 0, 3);
+        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO);
+        glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
+        glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT, 0);
 
         glfwSwapBuffers(window);
         glfwPollEvents();