diff --git a/domain-model.md b/domain-model.md
new file mode 100644
index 000000000..3dd8677a5
--- /dev/null
+++ b/domain-model.md
@@ -0,0 +1,20 @@
+
+## Domain Model ##
+| Classes      | Members                                                           | Methods                              | Scenario                                                           | Outputs                 |
+|--------------|-------------------------------------------------------------------|--------------------------------------|--------------------------------------------------------------------|-------------------------|
+| **TodoList** | `hashMap<String, Boolean> tasks` (key: name, value: true or false | boolean `addTask(String name)`       | If task with the provided name is nor in the to do list            | `true`                  |
+|              |                                                                   |                                      | Task with the provided name is already in to do list` → do nothing | `false`                 |
+|              |                                                                   | List<String> getAll()                | List that contains tasks                                           | HashMap<String, Boolean |
+|              |                                                                   | Boolean changeStatus(String name)    | Name exists, then flip status                                      | True                    |
+|              |                                                                   |                                      | Not found                                                          | False                   |
+|              |                                                                   | List<String> getCompleteTasks()      | when tasks are completed, then get completed tasks with name       | True                    |
+|              |                                                                   | List<String> getIncomplete           | look for incomplete tasks and return them                          | True                    |
+|              |                                                                   | List<String> getIncomplete           | All tasks completed or no tasks exist                              | empty List              |
+|              |                                                                   | String search(String name)           | found                                                              | String                  |
+|              |                                                                   |                                      | not found                                                          | String                  |
+|              |                                                                   | boolean remove(String name)          | found --> delete                                                   | True                    |
+|              |                                                                   |                                      | not found --> delete                                               | False                   |
+|              |                                                                   | List<String> sortedInAscendingOrder  | Go through list and sort                                           | String                  |
+|              |                                                                   | List<String> sortedInDescendingOrder | go through list and sort                                           | String                  |
+
+
diff --git a/src/main/java/com/booleanuk/core/TodoList.java b/src/main/java/com/booleanuk/core/TodoList.java
index 675adaf0b..37573d98f 100644
--- a/src/main/java/com/booleanuk/core/TodoList.java
+++ b/src/main/java/com/booleanuk/core/TodoList.java
@@ -1,5 +1,108 @@
 package com.booleanuk.core;
 
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.LinkedHashMap;
+
 public class TodoList {
+    HashMap<String, Boolean> tasks = new LinkedHashMap<>();
+
+
+    public Boolean addTask(String name) {
+        if (name == null)
+            return false;
+
+        String nTrim = name.trim();
+        if (nTrim.isEmpty())
+            return false;
+
+        if (tasks.containsKey(nTrim))
+            return false;
+
+
+        tasks.put(nTrim, false);
+            return true;
+
+        }
+
+
+
+    public ArrayList<String> getTasks() {
+        return new ArrayList<>(tasks.keySet());
+    }
+
+
+
+    public Boolean changeStatus(String name) {
+        if (name == null)
+            return false;
+        String nTrim = name.trim();
+
+        if (nTrim.isEmpty())
+            return false;
+
+        Boolean status = tasks.get(nTrim);
+        if (status == null)
+            return false;
+
+        tasks.put(nTrim, !status);
+        return true;
+
+    }
+
+    public ArrayList<String> getCompletedTasks() {
+        ArrayList<String> doneTasks = new ArrayList<>();
+        for (HashMap.Entry<String, Boolean> entry : tasks.entrySet()) {
+            if (entry.getValue() == true) {
+                doneTasks.add(entry.getKey());
+            }
+
+        }
+        return doneTasks;
+    }
+
+    public ArrayList<String> getIncompleteTasks() {
+        ArrayList<String> doneTasks = new ArrayList<>();
+        for (HashMap.Entry<String, Boolean> entry : tasks.entrySet()) {
+            if (entry.getValue() == false) {
+                doneTasks.add(entry.getKey());
+            }
+        }
+        return doneTasks;
+    }
+
+    public String search(String name){
+        String nTrim = name.trim();
+        if (tasks.containsKey(nTrim)) {
+            return nTrim;
+        }
+        return "Task not found";
+    }
+
+    public boolean deleteTask(String name){
+        if (name == null) {
+            return false;
+        }
+        String nTrim = name.trim();
+        if (nTrim.isEmpty()) {
+            return false;
+        }
+        return tasks.remove(nTrim) != null;
+    }
+
+    public ArrayList<String> sortTasksAscOrder(){
+        ArrayList<String> sortedTasks = new ArrayList<>(tasks.keySet());
+        Collections.sort(sortedTasks);
+        return sortedTasks;
+    }
+
+    public ArrayList<String> sortTasksDescOrder(){
+        ArrayList<String> sortedTasks = new ArrayList<>(tasks.keySet());
+        sortedTasks.sort(Collections.reverseOrder());
+        return sortedTasks;
+    }
+
+
 
 }
diff --git a/src/test/java/com/booleanuk/core/TodoListTest.java b/src/test/java/com/booleanuk/core/TodoListTest.java
index 0bef779a4..3cb703219 100644
--- a/src/test/java/com/booleanuk/core/TodoListTest.java
+++ b/src/test/java/com/booleanuk/core/TodoListTest.java
@@ -3,11 +3,143 @@
 import org.junit.jupiter.api.Assertions;
 import org.junit.jupiter.api.Test;
 
+import java.util.ArrayList;
+import java.util.HashMap;
+
 class TodoListTest {
+
+    @Test
+    public void addTaskWhenNewValidName() {
+        TodoList todo = new TodoList();
+        boolean result = todo.addTask("Play football today");
+        Assertions.assertTrue(result);
+
+
+    }
+
+    @Test
+    public void getFalseIfDuplicate() {
+        TodoList todo = new TodoList();
+        Assertions.assertTrue(todo.addTask("Play football today"));
+        Assertions.assertFalse(todo.addTask("Play football today"));
+    }
+    @Test
+    public void listAllTasks() {
+        TodoList todo = new TodoList();
+        // add tasks into the TodoList
+        todo.addTask("buy milk");
+        todo.addTask("buy cheese");
+        todo.addTask("go and run");
+
+        ArrayList<String> list = new ArrayList<>();
+        list.add("buy milk");
+        list.add("buy cheese");
+        list.add("go and run");
+
+        Assertions.assertEquals(list, todo.getTasks());
+    }
+
+    @Test
+    public void changeStatusOfTask() {
+        TodoList todo = new TodoList();
+        todo.addTask("buy cheese");
+        Assertions.assertTrue(todo.changeStatus("buy cheese"));
+        Assertions.assertTrue(todo.getCompletedTasks().contains("buy cheese"));
+
+        Assertions.assertTrue(todo.changeStatus("buy cheese"));
+        Assertions.assertTrue(todo.getIncompleteTasks().contains("buy cheese"));
+
+        Assertions.assertFalse(todo.changeStatus("Play football today"));
+        Assertions.assertFalse(todo.changeStatus("Non existent task"));
+
+    }
+
+    @Test
+    public void getTaskByCompletion() {
+        TodoList todo = new TodoList();
+        todo.addTask("run");
+        todo.addTask("buy milk");
+        todo.addTask("buy cheese");
+
+        todo.changeStatus("run");
+        todo.changeStatus("buy milk");
+
+        ArrayList<String> list = new ArrayList<>();
+        list.add("run");
+        list.add("buy milk");
+
+        Assertions.assertEquals(list, todo.getCompletedTasks());
+    }
+
+    @Test
+    public void getTasksByIncompletion() {
+        TodoList todo = new TodoList();
+        todo.addTask("cut hair");
+        todo.addTask("Write story");
+
+        Assertions.assertTrue(todo.changeStatus("Write story"));
+
+        ArrayList<String> list = new ArrayList<>();
+        list.add("cut hair");
+
+        Assertions.assertEquals(list, todo.getIncompleteTasks());
+    }
+
+    @Test
+    public void searchForTasksAndReturnMessageIfTaskNotFound() {
+        TodoList todo = new TodoList();
+
+        todo.addTask("Go and run");
+        todo.addTask("buy cheese");
+
+        String str = todo.search("clean table");
+        Assertions.assertEquals("Task not found", str);
+
+
+    }
+
     @Test
-    public void exampleTest() {
-        String hello = "Hello";
-        Assertions.assertEquals("Hello", hello);
-        Assertions.assertNotEquals("Goodbye", hello);
+    public void deleteTaskIfFound() {
+        TodoList todo = new TodoList();
+        todo.addTask("Go and run");
+        todo.addTask("buy cheese");
+        todo.addTask("buy food");
+
+
+        Assertions.assertTrue(todo.deleteTask("buy food"));
+        Assertions.assertFalse(todo.getTasks().contains("buy food"));
     }
+
+    @Test
+    public void sortedInAscendingOrder() {
+        TodoList todo = new  TodoList();
+        todo.addTask("C");
+        todo.addTask("A");
+        todo.addTask("B");
+
+        ArrayList<String> list = new ArrayList<>();
+        list.add("A");
+        list.add("B");
+        list.add("C");
+
+        Assertions.assertEquals(list, todo.sortTasksAscOrder());
+    }
+
+    @Test
+    public void sortedInDescendingOrder() {
+        TodoList todo = new TodoList();
+        todo.addTask("A");
+        todo.addTask("B");
+        todo.addTask("C");
+
+        ArrayList<String> list = new ArrayList<>();
+        list.add("C");
+        list.add("B");
+        list.add("A");
+
+        Assertions.assertEquals(list, todo.sortTasksDescOrder());
+    }
+
+
 }
+