diff --git a/domain-model.md b/domain-model.md
new file mode 100644
index 000000000..5431d8def
--- /dev/null
+++ b/domain-model.md
@@ -0,0 +1,30 @@
+
+ # TodoList class
+ 
+| Members                | Methods                                                | Scenarios                        | Result                      |
+|------------------------|--------------------------------------------------------|----------------------------------|-----------------------------|
+| ArrayList\<Task> tasks | boolean add(Task task)                                 | Task is already in list          | False                       |
+|                        |                                                        | Task is not in list              | True                        |
+|                        | ArrayList\<Task> viewTasks()                           |                                  | Return entire todo list     |
+|                        | ArrayList\<Task> viewIncompleteTasks()                 |                                  | Return incomplete task list |
+|                        | ArrayList\<Task> viewCompleteTasks()                   |                                  | Return complete task list   |
+|                        | Task searchTask(Task task)                             | Task not found                   | Return null + error message |
+|                        |                                                        | Task found                       | Return task                 |
+|                        | void removeTask(Task task)                             | Task to be removed doesn't exist | Do nothing                  |
+|                        |                                                        | Task to be removed exists        | Remove task from todo list  |
+|                        | ArrayList\<String> alphabeticallyAscView()             |                                  | Return sorted todo list     |
+|                        | ArrayList\<String> alphabeticallyDescView()            |                                  | Return sorted todo list     |
+|                        | void updateTaskNameByID(UUID uid, String newName)      | Invalid ID or task doesn't exist | Do nothing                  |
+|                        |                                                        | Valid ID and task exists         | Update the task name        |
+|                        | void updateTaskStatusByID(UUID uid, boolean newStatus) | Invalid ID or task doesn't exist | Do nothing                  |
+|                        |                                                        | Valid ID and task exists         | Update the task status      |
+|                        | TaskExtension getTaskByID(UUID uid)                    | Invalid ID or task doesn't exist | Do nothing                  |
+|                        |                                                        | Valid ID and task exists         | Return the task by ID       |
+
+# Task class
+
+| Members          | Methods                           | Scenarios       | Result                        |
+|------------------|-----------------------------------|-----------------|-------------------------------|
+| boolean complete | void changeStatus(boolean status) | status is true  | Member complete becomes true  |
+| String name      |                                   | status is false | Member complete becomes false |
+| UUID uid         |                                   |                 |                               |
diff --git a/src/main/java/com/booleanuk/core/Task.java b/src/main/java/com/booleanuk/core/Task.java
new file mode 100644
index 000000000..974f9323b
--- /dev/null
+++ b/src/main/java/com/booleanuk/core/Task.java
@@ -0,0 +1,16 @@
+package com.booleanuk.core;
+
+public class Task {
+    String name;
+    boolean complete;
+
+    public Task(String name) {
+        this.name = name;
+        this.complete = false;
+
+    }
+
+    public void changeStatus(boolean status) {
+        this.complete = status;
+    }
+}
diff --git a/src/main/java/com/booleanuk/core/TodoList.java b/src/main/java/com/booleanuk/core/TodoList.java
index 675adaf0b..3bb791ee5 100644
--- a/src/main/java/com/booleanuk/core/TodoList.java
+++ b/src/main/java/com/booleanuk/core/TodoList.java
@@ -1,5 +1,77 @@
 package com.booleanuk.core;
 
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+import java.util.Comparator;
+
 public class TodoList {
 
+    ArrayList<Task> tasks = new ArrayList<>();
+
+
+    public boolean add(Task task) {
+        if (!tasks.contains(task)) {
+            tasks.add(task);
+            return true;
+        }
+        return false;
+    }
+
+    public ArrayList<Task> viewTasks() {
+        return tasks;
+    }
+
+    public ArrayList<Task> viewIncompleteTasks() {
+        ArrayList<Task> incomplete = new ArrayList<>();
+        for (Task task : this.tasks) {
+            if (!task.complete) {
+                incomplete.add(task);
+            }
+        }
+        return incomplete;
+    }
+
+    public ArrayList<Task> viewCompleteTasks() {
+        ArrayList<Task> complete = new ArrayList<>();
+        for (Task task : this.tasks) {
+            if (task.complete) {
+                complete.add(task);
+            }
+        }
+        return complete;
+    }
+
+    Task searchTask(Task task) {
+        if(tasks.contains(task)) {
+            return task;
+        }
+        System.out.println("Task not found!");
+        return null;
+    }
+
+    void removeTask(Task task) {
+        this.tasks.remove(task);
+
+    }
+
+    ArrayList<String> alphabeticallyAscView() {
+        ArrayList<String> results = new ArrayList<>();
+        for (Task task : this.tasks) {
+            results.add(task.name);
+
+        }
+        results.sort(null);
+        return results;
+    }
+
+    ArrayList<String> alphabeticallyDescView() {
+        ArrayList<String> results = new ArrayList<>();
+        for (Task task : this.tasks) {
+            results.add(task.name);
+
+        }
+        results.sort(Comparator.reverseOrder());
+        return results;
+    }
+
 }
diff --git a/src/main/java/com/booleanuk/extension/TaskExtension.java b/src/main/java/com/booleanuk/extension/TaskExtension.java
new file mode 100644
index 000000000..e7c9fbecb
--- /dev/null
+++ b/src/main/java/com/booleanuk/extension/TaskExtension.java
@@ -0,0 +1,20 @@
+package com.booleanuk.extension;
+import java.util.UUID;
+
+public class TaskExtension {
+    String name;
+    boolean complete;
+    UUID uid;
+
+    public TaskExtension(String name) {
+        this.name = name;
+        this.complete = false;
+        this.uid = UUID.randomUUID();
+
+    }
+
+    public void changeStatus(boolean status) {
+        this.complete = status;
+    }
+
+}
diff --git a/src/main/java/com/booleanuk/extension/TodoListExtension.java b/src/main/java/com/booleanuk/extension/TodoListExtension.java
new file mode 100644
index 000000000..c6c7f8410
--- /dev/null
+++ b/src/main/java/com/booleanuk/extension/TodoListExtension.java
@@ -0,0 +1,101 @@
+package com.booleanuk.extension;
+
+import java.util.ArrayList;
+import java.util.Comparator;
+import java.util.UUID;
+
+public class TodoListExtension {
+
+    ArrayList<TaskExtension> tasks = new ArrayList<>();
+
+
+    public boolean add(TaskExtension task) {
+        if (!tasks.contains(task)) {
+            tasks.add(task);
+            return true;
+        }
+        return false;
+    }
+
+    public ArrayList<TaskExtension> viewTasks() {
+        return tasks;
+    }
+
+    public ArrayList<TaskExtension> viewIncompleteTasks() {
+        ArrayList<TaskExtension> incomplete = new ArrayList<>();
+        for (TaskExtension task : this.tasks) {
+            if (!task.complete) {
+                incomplete.add(task);
+            }
+        }
+        return incomplete;
+    }
+
+    public ArrayList<TaskExtension> viewCompleteTasks() {
+        ArrayList<TaskExtension> complete = new ArrayList<>();
+        for (TaskExtension task : this.tasks) {
+            if (task.complete) {
+                complete.add(task);
+            }
+        }
+        return complete;
+    }
+
+    public TaskExtension searchTask(TaskExtension task) {
+        if(tasks.contains(task)) {
+            return task;
+        }
+        System.out.println("Task not found!");
+        return null;
+    }
+
+    public void removeTask(TaskExtension task) {
+        this.tasks.remove(task);
+
+    }
+
+    ArrayList<String> alphabeticallyAscView() {
+        ArrayList<String> names = new ArrayList<>();
+        for (TaskExtension task : this.tasks) {
+            names.add(task.name);
+
+        }
+        names.sort(null);
+        return names;
+    }
+
+    ArrayList<String> alphabeticallyDescView() {
+        ArrayList<String> names = new ArrayList<>();
+        for (TaskExtension task : this.tasks) {
+            names.add(task.name);
+
+        }
+        names.sort(Comparator.reverseOrder());
+        return names;
+    }
+
+    public void updateTaskNameByID(UUID uid, String newName)  {
+        for (TaskExtension task : this.tasks) {
+            if (task.uid == uid) {
+                task.name = newName;
+            }
+        }
+    }
+
+    public void updateTaskStatusByID(UUID uid, boolean newStatus) {
+        for (TaskExtension task : this.tasks) {
+            if (task.uid == uid) {
+                task.changeStatus(newStatus);
+            }
+        }
+    }
+
+    TaskExtension getTaskByID(UUID uid) {
+        for (TaskExtension task : this.tasks) {
+            if (task.uid == uid) {
+                return task;
+            }
+        } return null;
+    }
+
+}
diff --git a/src/test/java/com/booleanuk/core/TaskTest.java b/src/test/java/com/booleanuk/core/TaskTest.java
new file mode 100644
index 000000000..28b6be030
--- /dev/null
+++ b/src/test/java/com/booleanuk/core/TaskTest.java
@@ -0,0 +1,18 @@
+package com.booleanuk.core;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class TaskTest {
+    @Test
+    public void testStatusChanges(){
+        Task testTask = new Task("TestTask");
+        testTask.changeStatus(true);
+        Assertions.assertTrue(testTask.complete);
+        testTask.changeStatus(false);
+        Assertions.assertFalse(testTask.complete);
+    }
+
+
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/booleanuk/core/TodoListTest.java b/src/test/java/com/booleanuk/core/TodoListTest.java
index 0bef779a4..77b31434c 100644
--- a/src/test/java/com/booleanuk/core/TodoListTest.java
+++ b/src/test/java/com/booleanuk/core/TodoListTest.java
@@ -3,11 +3,116 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.lang.reflect.Array;
+import java.util.ArrayList;
+
 class TodoListTest {
     @Test
-    public void exampleTest() {
-        String hello = "Hello";
-        Assertions.assertEquals("Hello", hello);
-        Assertions.assertNotEquals("Goodbye", hello);
+    public void checkForTaskInList() {
+        Task task = new Task("Test");
+        TodoList todo = new TodoList();
+        Assertions.assertTrue(todo.add(task));
+        Assertions.assertFalse(todo.add(task));
+
+    }
+
+    @Test
+    public void checkViewTask() {
+        Task task = new Task("Test");
+        TodoList todo = new TodoList();
+        ArrayList<Task> empty = new ArrayList<>();
+        Assertions.assertIterableEquals(empty, todo.viewTasks());
+        todo.add(task);
+        empty.add(task);
+        Assertions.assertIterableEquals(empty, todo.viewTasks());
+
+    }
+
+    @Test
+    public void checkIncompleteTaskView() {
+        TodoList todo = new TodoList();
+        Task taskIncomplete = new Task("Task incomplete");
+        Task taskComplete = new Task("Task complete");
+        taskComplete.changeStatus(true);
+        todo.add(taskIncomplete);
+        todo.add(taskComplete);
+        Assertions.assertNotEquals(todo.viewTasks(), todo.viewIncompleteTasks());
+    }
+
+    @Test
+    public void checkCompleteTaskView() {
+        TodoList todo = new TodoList();
+        Task taskIncomplete = new Task("Task incomplete");
+        Task taskComplete = new Task("Task complete");
+        taskComplete.changeStatus(true);
+        todo.add(taskIncomplete);
+        todo.add(taskComplete);
+        Assertions.assertNotEquals(todo.viewTasks(), todo.viewCompleteTasks());
+    }
+
+    @Test
+    public void testSearchTaskName() {
+        TodoList todo = new TodoList();
+        Task example = new Task("Example");
+
+        Assertions.assertNotEquals(example, todo.searchTask(example));
+        todo.add(example);
+
+        Assertions.assertEquals(example, todo.searchTask(example));
+
+    }
+
+    @Test
+    public void testRemoveTask() {
+        TodoList todo = new TodoList();
+        Task example = new Task("Example");
+        Task example2 = new Task("Example2");
+
+        todo.add(example);
+        ArrayList<Task> tasks = todo.viewTasks();
+        todo.removeTask(example2);
+        Assertions.assertEquals(tasks, todo.viewTasks());
+
+        todo.add(example2);
+        int tasks_size = todo.tasks.size();
+        todo.removeTask(example2);
+        Assertions.assertNotEquals(todo.tasks.size(), tasks_size);
+
     }
+
+    @Test
+    public void testAscending() {
+        TodoList todo = new TodoList();
+        Task a = new Task("A");
+        Task z = new Task("Zebra");
+        Task f = new Task("Fair");
+
+        todo.add(z);
+        todo.add(f);
+        todo.add(a);
+
+        Assertions.assertNotEquals(todo.viewTasks().get(0).name, todo.alphabeticallyAscView().get(0));
+        Assertions.assertEquals(todo.viewTasks().get(1).name, todo.alphabeticallyAscView().get(1));
+        Assertions.assertNotEquals(todo.viewTasks().get(2).name, todo.alphabeticallyAscView().get(2));
+
+    }
+
+
+    @Test
+    public void testDescending() {
+        TodoList todo = new TodoList();
+        Task a = new Task("A");
+        Task z = new Task("Zebra");
+        Task f = new Task("Fair");
+
+        todo.add(z);
+        todo.add(f);
+        todo.add(a);
+
+        Assertions.assertEquals(todo.viewTasks().get(0).name, todo.alphabeticallyDescView().get(0));
+        Assertions.assertEquals(todo.viewTasks().get(1).name, todo.alphabeticallyDescView().get(1));
+        Assertions.assertEquals(todo.viewTasks().get(2).name, todo.alphabeticallyDescView().get(2));
+
+    }
+
 }
diff --git a/src/test/java/com/booleanuk/extension/TaskExtensionTest.java b/src/test/java/com/booleanuk/extension/TaskExtensionTest.java
new file mode 100644
index 000000000..69f2c2e0e
--- /dev/null
+++ b/src/test/java/com/booleanuk/extension/TaskExtensionTest.java
@@ -0,0 +1,16 @@
+package com.booleanuk.extension;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+class TaskExtensionTest {
+    @Test
+    public void testStatusChanges(){
+        TaskExtension testTask = new TaskExtension("TestTask");
+        testTask.changeStatus(true);
+        Assertions.assertTrue(testTask.complete);
+        testTask.changeStatus(false);
+        Assertions.assertFalse(testTask.complete);
+    }
+
+}
\ No newline at end of file
diff --git a/src/test/java/com/booleanuk/extension/TodoListExtensionTest.java b/src/test/java/com/booleanuk/extension/TodoListExtensionTest.java
new file mode 100644
index 000000000..5203639b7
--- /dev/null
+++ b/src/test/java/com/booleanuk/extension/TodoListExtensionTest.java
@@ -0,0 +1,150 @@
+package com.booleanuk.extension;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.util.ArrayList;
+import java.util.UUID;
+
+class TodoListExtensionTest {
+    @Test
+    public void checkForTaskInList() {
+        TaskExtension task = new TaskExtension("Test");
+        TodoListExtension todo = new TodoListExtension();
+        Assertions.assertTrue(todo.add(task));
+        Assertions.assertFalse(todo.add(task));
+
+    }
+
+    @Test
+    public void checkViewTask() {
+        TaskExtension task = new TaskExtension("Test");
+        TodoListExtension todo = new TodoListExtension();
+        ArrayList<TaskExtension> empty = new ArrayList<>();
+        Assertions.assertIterableEquals(empty, todo.viewTasks());
+        todo.add(task);
+        empty.add(task);
+        Assertions.assertIterableEquals(empty, todo.viewTasks());
+
+    }
+
+    @Test
+    public void checkIncompleteTaskView() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension taskIncomplete = new TaskExtension("Task incomplete");
+        TaskExtension taskComplete = new TaskExtension("Task complete");
+        taskComplete.changeStatus(true);
+        todo.add(taskIncomplete);
+        todo.add(taskComplete);
+        Assertions.assertNotEquals(todo.viewTasks(), todo.viewIncompleteTasks());
+    }
+
+    @Test
+    public void checkCompleteTaskView() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension taskIncomplete = new TaskExtension("Task incomplete");
+        TaskExtension taskComplete = new TaskExtension("Task complete");
+        taskComplete.changeStatus(true);
+        todo.add(taskIncomplete);
+        todo.add(taskComplete);
+        Assertions.assertNotEquals(todo.viewTasks(), todo.viewCompleteTasks());
+    }
+
+    @Test
+    public void testSearchTaskName() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension example = new TaskExtension("Example");
+
+        Assertions.assertNotEquals(example, todo.searchTask(example));
+        todo.add(example);
+
+        Assertions.assertEquals(example, todo.searchTask(example));
+
+    }
+
+    @Test
+    public void testRemoveTask() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension example = new TaskExtension("Example");
+        TaskExtension example2 = new TaskExtension("Example2");
+
+        todo.add(example);
+        ArrayList<TaskExtension> tasks = todo.viewTasks();
+        todo.removeTask(example2);
+        Assertions.assertEquals(tasks, todo.viewTasks());
+
+        todo.add(example2);
+        int tasks_size = todo.tasks.size();
+        todo.removeTask(example2);
+        Assertions.assertNotEquals(todo.tasks.size(), tasks_size);
+
+    }
+
+    @Test
+    public void testAscending() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension a = new TaskExtension("A");
+        TaskExtension z = new TaskExtension("Zebra");
+        TaskExtension f = new TaskExtension("Fair");
+
+        todo.add(z);
+        todo.add(f);
+        todo.add(a);
+
+        Assertions.assertNotEquals(todo.viewTasks().get(0).name, todo.alphabeticallyAscView().get(0));
+        Assertions.assertEquals(todo.viewTasks().get(1).name, todo.alphabeticallyAscView().get(1));
+        Assertions.assertNotEquals(todo.viewTasks().get(2).name, todo.alphabeticallyAscView().get(2));
+
+    }
+
+
+    @Test
+    public void testDescending() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension a = new TaskExtension("A");
+        TaskExtension z = new TaskExtension("Zebra");
+        TaskExtension f = new TaskExtension("Fair");
+
+        todo.add(z);
+        todo.add(f);
+        todo.add(a);
+
+        Assertions.assertEquals(todo.viewTasks().get(0).name, todo.alphabeticallyDescView().get(0));
+        Assertions.assertEquals(todo.viewTasks().get(1).name, todo.alphabeticallyDescView().get(1));
+        Assertions.assertEquals(todo.viewTasks().get(2).name, todo.alphabeticallyDescView().get(2));
+
+    }
+
+    @Test
+    public void testUpdateName() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension task = new TaskExtension("Task1");
+        UUID taskID = task.uid;
+        todo.add(task);
+        todo.updateTaskNameByID(taskID, "new Name");
+        Assertions.assertEquals("new Name", task.name);
+    }
+
+    @Test
+    public void testUpdateStatus() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension task = new TaskExtension("Task1");
+        UUID taskID = task.uid;
+        todo.add(task);
+        todo.updateTaskStatusByID(taskID, true);
+        Assertions.assertTrue(task.complete);
+        todo.updateTaskStatusByID(taskID, false);
+        Assertions.assertFalse(task.complete);
+    }
+
+    @Test
+    public void testGetTask() {
+        TodoListExtension todo = new TodoListExtension();
+        TaskExtension task = new TaskExtension("Task1");
+        UUID taskID = task.uid;
+        todo.add(task);
+        TaskExtension testTask = todo.getTaskByID(taskID);
+        Assertions.assertEquals(task, testTask);
+    }
+
+}