diff --git a/polls/migrations/0015_question_trend_score.py b/polls/migrations/0015_question_trend_score.py
new file mode 100644
index 0000000..6b1b3a9
--- /dev/null
+++ b/polls/migrations/0015_question_trend_score.py
@@ -0,0 +1,18 @@
+# Generated by Django 4.2.4 on 2023-09-15 07:23
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('polls', '0014_remove_question_down_vote_count_and_more'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='question',
+            name='trend_score',
+            field=models.FloatField(default=0.0),
+        ),
+    ]
diff --git a/polls/models.py b/polls/models.py
index 70995ff..3fd50d5 100644
--- a/polls/models.py
+++ b/polls/models.py
@@ -46,6 +46,7 @@ class Question(models.Model):
     end_date = models.DateTimeField("date ended", null=True)
     short_description = models.CharField(max_length=200, default="Cool kids have polls")
     long_description = models.TextField(max_length=2000, default="No description provide for this poll.")
+    trend_score = models.FloatField(default=0.0, null=False, blank=False)
     tags = models.ManyToManyField(Tag, blank=True)
 
     def was_published_recently(self):
@@ -157,6 +158,9 @@ class Question(models.Model):
 
     # ! Most of the code from https://stackoverflow.com/a/70869267
     def upvote(self, user):
+        """create new SentimentVote object that represent upvote (vote_types=True)
+        return True if user change the vote or vote for the first time else return False
+        """
         try:
             self.sentimentvote_set.create(user=user, question=self, vote_types=True)
             self.save()
@@ -170,6 +174,9 @@ class Question(models.Model):
         return True
 
     def downvote(self, user):
+        """create new SentimentVote object that represent downvote (vote_types=False)
+        return True if user change the vote or vote for the first time else return False
+        """
         try:
             self.sentimentvote_set.create(user=user, question=self, vote_types=False)
             self.save()
@@ -190,6 +197,38 @@ class Question(models.Model):
     def down_vote_count(self):
         return self.sentimentvote_set.filter(question=self, vote_types=False).count()
 
+    def trending_score(self, up=None, down=None):
+        """Return trend score base on the criteria below"""
+        published_date_duration = timezone.now() - self.pub_date
+        score = 0
+
+        if (published_date_duration.seconds  < 259200): # Second unit
+                score += 100
+        elif (published_date_duration.seconds < 604800):
+            score += 75
+        elif (published_date_duration.seconds < 2592000):
+            score += 50
+        else:
+            score += 25
+
+        if (up == None) and (down == None):
+            score += ((self.up_vote_count/5) - (self.down_vote_count/5)) * 100
+        else:
+            score += ((up/5) - (down/5)) * 100
+
+        return score
+
+
+    def save(self, *args, **kwargs):
+        """Modify save method of Question object"""
+        # to-be-added instance # * https://github.com/django/django/blob/866122690dbe233c054d06f6afbc2f3cc6aea2f2/django/db/models/base.py#L447
+        if self._state.adding:
+            try:
+                self.trend_score = self.trending_score()
+            except ValueError:
+                self.trend_score = self.trending_score(up=0, down=0)
+        super(Question, self).save(*args, **kwargs)
+
 
 class Choice(models.Model):
     """
@@ -228,9 +267,25 @@ class Vote(models.Model):
 
 # ! Most of the code from https://stackoverflow.com/a/70869267
 class SentimentVote(models.Model):
+    """
+    Represents a sentiment vote for a poll question.
+
+    Attributes:
+        user (User): The user who cast the sentiment vote.
+        question (Question): The poll question for which the sentiment vote is cast.
+        vote_types (bool): Indicates whether the sentiment vote is an upvote (True) or a downvote (False).
+
+    Note:
+        - When 'vote_types' is True, it represents an upvote or 'Like'.
+        - When 'vote_types' is False, it represents a downvote or 'Dislike'.
+    """
     user = models.ForeignKey(User, on_delete=models.CASCADE)
     question = models.ForeignKey(Question, on_delete=models.CASCADE)
     vote_types = models.BooleanField()
 
     class Meta:
+        """
+        unique_together (list of str): Ensures that a user can only cast one sentiment vote (upvote or downvote)
+        for a specific question.
+        """
         unique_together = ['user', 'question']
\ No newline at end of file
diff --git a/polls/templates/polls/index.html b/polls/templates/polls/index.html
index fb8fdb2..0dd54a0 100644
--- a/polls/templates/polls/index.html
+++ b/polls/templates/polls/index.html
@@ -83,7 +83,7 @@
         <h2 class="text-2xl font-bold bg-gradient-to-r from-red-600 via-orange-600 to-yellow-600 bg-clip-text text-transparent lg:inline">Top Polls Today</h2>
         <hr class="h-px my-4 bg-gray-200 border-0 dark:bg-gray-400" />
         <div class="grid grid-cols-1 gap-4 md:grid-cols-2 lg:grid-cols-3">
-          {% for question in latest_question_list %}
+          {% for question in latest_question_list.trend_poll %}
           <div class="relative">
             <!-- INFO -->
             <div class="rounded-lg bg-white p-4 shadow-md border-solid border-2 border-yellow-500 relative z-10 transform translate-y-0 hover:translate-y-1 transition-transform">
@@ -129,7 +129,7 @@
         <h2 class="mb-4 text-2xl font-bold">All Polls</h2>
         <hr class="h-px my-4 bg-gray-200 border-0 dark:bg-gray-400" />
         <div class="grid grid-cols-1 gap-4 md:grid-cols-2 lg:grid-cols-2 xl:grid-cols-3">
-          {% for question in latest_question_list %}
+          {% for question in latest_question_list.all_poll %}
           <div class="relative">
             <!-- INFO -->
             <div class="rounded-lg bg-white p-4 shadow-md border-solid border-2 border-neutral-500 relative z-10 transform translate-y-0 hover:translate-y-1 transition-transform">
diff --git a/polls/tests/test_index_views.py b/polls/tests/test_index_views.py
index 4cf0ad2..911dac1 100644
--- a/polls/tests/test_index_views.py
+++ b/polls/tests/test_index_views.py
@@ -12,7 +12,7 @@ class QuestionIndexViewTests(TestCase):
         """
         response = self.client.get(reverse("polls:index"))
         self.assertEqual(response.status_code, 200)
-        self.assertQuerySetEqual(response.context["latest_question_list"], [])
+        self.assertQuerySetEqual(response.context["latest_question_list"]["all_poll"], [])
 
     def test_past_question(self):
         """
@@ -24,7 +24,7 @@ class QuestionIndexViewTests(TestCase):
         question.save()
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
-            response.context["latest_question_list"],
+            response.context["latest_question_list"]["all_poll"],
             [question],
         )
 
@@ -37,7 +37,7 @@ class QuestionIndexViewTests(TestCase):
         future_question.pub_date = timezone.now() + timezone.timedelta(days=30)
         future_question.save()
         response = self.client.get(reverse("polls:index"))
-        self.assertQuerySetEqual(response.context["latest_question_list"], [])
+        self.assertQuerySetEqual(response.context["latest_question_list"]["all_poll"], [])
 
     def test_future_question_and_past_question(self):
         """
@@ -54,7 +54,7 @@ class QuestionIndexViewTests(TestCase):
 
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
-            response.context["latest_question_list"],
+            response.context["latest_question_list"]["all_poll"],
             [past_question],
         )
 
@@ -72,6 +72,6 @@ class QuestionIndexViewTests(TestCase):
 
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
-            response.context["latest_question_list"],
+            response.context["latest_question_list"]["all_poll"],
             [question2, question1],
         )
diff --git a/polls/tests/test_question_model.py b/polls/tests/test_question_model.py
index 6514de0..f0cdd07 100644
--- a/polls/tests/test_question_model.py
+++ b/polls/tests/test_question_model.py
@@ -52,7 +52,7 @@ class QuestionModelTests(TestCase):
 
         response = self.client.get(reverse("polls:index"))
         self.assertQuerySetEqual(
-            response.context["latest_question_list"],
+            response.context["latest_question_list"]["all_poll"],
             [question],
         )
 
diff --git a/polls/tests/test_sentiment_model.py b/polls/tests/test_sentiment_model.py
new file mode 100644
index 0000000..c1ede3b
--- /dev/null
+++ b/polls/tests/test_sentiment_model.py
@@ -0,0 +1,42 @@
+from django.test import TransactionTestCase, Client
+from django.contrib.auth.models import User
+
+from .base import create_question
+from ..views import up_down_vote
+
+# ! https://stackoverflow.com/questions/24588520/testing-several-integrityerrors-in-the-same-django-unittest-test-case
+# * https://stackoverflow.com/questions/44450533/difference-between-testcase-and-transactiontestcase-classes-in-django-test
+class UpDownVoteViewTest(TransactionTestCase):
+    @classmethod
+    def setUp(cls) -> None:
+        cls.user = User.objects.create_user(username="test_user", password="12345abc")
+        cls.q1 = create_question(question_text="test 1")
+        cls.client = Client()
+
+    def test_vote_up_once(self):
+        self.client.login(username="test_user", password="12345abc")
+        self.q1.upvote(self.user)
+        self.assertFalse(self.q1.upvote(self.user))
+
+    def test_vote_down_once(self):
+        self.client.login(username="test_user", password="12345abc")
+        self.q1.downvote(self.user)
+        self.assertFalse(self.q1.downvote(self.user))
+
+    def test_can_change_up_to_down(self):
+        self.client.login(username="test_user", password="12345abc")
+        self.q1.upvote(self.user)
+        self.q1.downvote(self.user)
+        count_up = self.q1.sentimentvote_set.filter(vote_types=True).count()
+        count_down = self.q1.sentimentvote_set.filter(vote_types=False).count()
+        self.assertEqual(count_up, 0)
+        self.assertEqual(count_down, 1)
+
+    def test_can_change_up_to_down(self):
+        self.client.login(username="test_user", password="12345abc")
+        self.q1.downvote(self.user)
+        self.q1.upvote(self.user)
+        count_up = self.q1.sentimentvote_set.filter(vote_types=True).count()
+        count_down = self.q1.sentimentvote_set.filter(vote_types=False).count()
+        self.assertEqual(count_up, 1)
+        self.assertEqual(count_down, 0)
\ No newline at end of file
diff --git a/polls/views.py b/polls/views.py
index 1af2b09..b3b2907 100644
--- a/polls/views.py
+++ b/polls/views.py
@@ -8,6 +8,7 @@ from django.utils import timezone
 from django.urls import reverse_lazy, reverse
 from django.contrib.auth.mixins import LoginRequiredMixin
 from django.contrib import messages
+from django.contrib.auth import authenticate, login
 from django.contrib.auth.decorators import login_required
 from django.db.models import Q
 
@@ -29,10 +30,18 @@ class IndexView(generic.ListView):
             Return the last published questions that is published and haven't ended yet.
             """
             now = timezone.now()
-            return Question.objects.filter(
+            all_poll_queryset = Question.objects.filter(
                 Q(pub_date__lte=now) & ((Q(end_date__gte=now) | Q(end_date=None)))
             ).order_by("-pub_date")
 
+            trend_poll_queryset = Question.objects.filter(
+                Q(pub_date__lte=now) & ((Q(end_date__gte=now) | Q(end_date=None))) & Q(trend_score__gte=100)
+            ).order_by("trend_score")[:3]
+
+            queryset = {'all_poll' : all_poll_queryset,
+                        'trend_poll' : trend_poll_queryset,}
+            return queryset
+
 
 class DetailView(LoginRequiredMixin, generic.DetailView):
     """
@@ -105,6 +114,13 @@ class SignUpView(generic.CreateView):
     success_url = reverse_lazy('login')
     template_name = 'registration/signup.html'
 
+    def form_valid(self, form):
+        valid = super(SignUpView, self).form_valid(form)
+        username, password = form.cleaned_data.get("username"), form.cleaned_data.get("password1")
+        user = authenticate(username=username, password=password)
+        login(self.request, user)
+        return valid
+
 
 @login_required
 def vote(request, question_id):