diff --git a/app/models/image.rb b/app/models/image.rb
index d6ecd36..6443fa1 100644
--- a/app/models/image.rb
+++ b/app/models/image.rb
@@ -1,5 +1,8 @@
 class Image < ApplicationRecord
   has_one_attached :file
 
+  has_many :taggings, as: :taggable
+  has_many :tags, through: :taggings
+
   validates :title, :file, presence: true
 end
diff --git a/app/models/post.rb b/app/models/post.rb
new file mode 100644
index 0000000..80800c8
--- /dev/null
+++ b/app/models/post.rb
@@ -0,0 +1,6 @@
+class Post < ApplicationRecord
+  belongs_to :user
+  belongs_to :image
+  has_many :taggings, as: :taggable
+  has_many :tags, through: :taggings
+end
diff --git a/app/models/tag.rb b/app/models/tag.rb
new file mode 100644
index 0000000..c4d1c12
--- /dev/null
+++ b/app/models/tag.rb
@@ -0,0 +1,5 @@
+class Tag < ApplicationRecord
+  has_many :taggings
+  has_many :posts, through: :taggings, source: :taggable, source_type: "Post"
+  has_many :images, through: :taggings, source: :taggable, source_type: "Image"
+end
diff --git a/app/models/tagging.rb b/app/models/tagging.rb
new file mode 100644
index 0000000..e608dcd
--- /dev/null
+++ b/app/models/tagging.rb
@@ -0,0 +1,4 @@
+class Tagging < ApplicationRecord
+  belongs_to :tag
+  belongs_to :taggable, polymorphic: true
+end
diff --git a/app/models/user.rb b/app/models/user.rb
index d67da20..15bd0f0 100644
--- a/app/models/user.rb
+++ b/app/models/user.rb
@@ -1,3 +1,6 @@
 class User < ApplicationRecord
   has_secure_password
+  has_many :posts
+
+  validates :name, :status, :email, :password_digest, presence: true
 end
diff --git a/db/migrate/20250515134517_create_posts.rb b/db/migrate/20250515134517_create_posts.rb
new file mode 100644
index 0000000..a118eb8
--- /dev/null
+++ b/db/migrate/20250515134517_create_posts.rb
@@ -0,0 +1,14 @@
+class CreatePosts < ActiveRecord::Migration[8.0]
+  def change
+    create_table :posts do |t|
+      t.string :title
+      t.text :content
+      t.boolean :pinned
+      t.references :user, null: false, foreign_key: true
+      t.references :image, null: false, foreign_key: true
+      t.string :type
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20250515134851_create_tags.rb b/db/migrate/20250515134851_create_tags.rb
new file mode 100644
index 0000000..391a7fc
--- /dev/null
+++ b/db/migrate/20250515134851_create_tags.rb
@@ -0,0 +1,10 @@
+class CreateTags < ActiveRecord::Migration[8.0]
+  def change
+    create_table :tags do |t|
+      t.string :title
+      t.string :color
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/migrate/20250515135623_create_taggings.rb b/db/migrate/20250515135623_create_taggings.rb
new file mode 100644
index 0000000..505d687
--- /dev/null
+++ b/db/migrate/20250515135623_create_taggings.rb
@@ -0,0 +1,10 @@
+class CreateTaggings < ActiveRecord::Migration[8.0]
+  def change
+    create_table :taggings do |t|
+      t.references :tag, null: false, foreign_key: true
+      t.references :taggable, polymorphic: true, null: false
+
+      t.timestamps
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index e9f3ea9..edbe99a 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -10,7 +10,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema[8.0].define(version: 2025_05_08_131043) do
+ActiveRecord::Schema[8.0].define(version: 2025_05_15_135623) do
   create_table "active_storage_attachments", force: :cascade do |t|
     t.string "name", null: false
     t.string "record_type", null: false
@@ -45,6 +45,36 @@ ActiveRecord::Schema[8.0].define(version: 2025_05_08_131043) do
     t.datetime "updated_at", null: false
   end
 
+  create_table "posts", force: :cascade do |t|
+    t.string "title"
+    t.text "content"
+    t.boolean "pinned"
+    t.integer "user_id", null: false
+    t.integer "image_id", null: false
+    t.string "type"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["image_id"], name: "index_posts_on_image_id"
+    t.index ["user_id"], name: "index_posts_on_user_id"
+  end
+
+  create_table "taggings", force: :cascade do |t|
+    t.integer "tag_id", null: false
+    t.string "taggable_type", null: false
+    t.integer "taggable_id", null: false
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+    t.index ["tag_id"], name: "index_taggings_on_tag_id"
+    t.index ["taggable_type", "taggable_id"], name: "index_taggings_on_taggable"
+  end
+
+  create_table "tags", force: :cascade do |t|
+    t.string "title"
+    t.string "color"
+    t.datetime "created_at", null: false
+    t.datetime "updated_at", null: false
+  end
+
   create_table "users", force: :cascade do |t|
     t.string "name"
     t.string "status"
@@ -56,4 +86,7 @@ ActiveRecord::Schema[8.0].define(version: 2025_05_08_131043) do
 
   add_foreign_key "active_storage_attachments", "active_storage_blobs", column: "blob_id"
   add_foreign_key "active_storage_variant_records", "active_storage_blobs", column: "blob_id"
+  add_foreign_key "posts", "images"
+  add_foreign_key "posts", "users"
+  add_foreign_key "taggings", "tags"
 end
diff --git a/test/fixtures/files/mermaid_template.png b/test/fixtures/files/mermaid_template.png
new file mode 100644
index 0000000..6028901
Binary files /dev/null and b/test/fixtures/files/mermaid_template.png differ
diff --git a/test/fixtures/posts.yml b/test/fixtures/posts.yml
new file mode 100644
index 0000000..7f12185
--- /dev/null
+++ b/test/fixtures/posts.yml
@@ -0,0 +1,17 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  title: MyString
+  content: MyText
+  pinned: false
+  user: one
+  image: one
+  type: 
+
+two:
+  title: MyString
+  content: MyText
+  pinned: false
+  user: two
+  image: two
+  type: 
diff --git a/test/fixtures/taggings.yml b/test/fixtures/taggings.yml
new file mode 100644
index 0000000..b8346f1
--- /dev/null
+++ b/test/fixtures/taggings.yml
@@ -0,0 +1,11 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  tag: one
+  taggable: one
+  taggable_type: Taggable
+
+two:
+  tag: two
+  taggable: two
+  taggable_type: Taggable
diff --git a/test/fixtures/tags.yml b/test/fixtures/tags.yml
new file mode 100644
index 0000000..73a1e08
--- /dev/null
+++ b/test/fixtures/tags.yml
@@ -0,0 +1,9 @@
+# Read about fixtures at https://api.rubyonrails.org/classes/ActiveRecord/FixtureSet.html
+
+one:
+  title: MyString
+  color: MyString
+
+two:
+  title: MyString
+  color: MyString
diff --git a/test/fixtures/users.yml b/test/fixtures/users.yml
index 6956558..687c436 100644
--- a/test/fixtures/users.yml
+++ b/test/fixtures/users.yml
@@ -4,4 +4,10 @@ one:
   name: testuser
   status: test
   email: test@email.com
-  password_digest: <%= BCrypt::Password.create('testpassword') %>
\ No newline at end of file
+  password_digest: <%= BCrypt::Password.create('testpassword') %>
+
+two:
+  name: testuser2
+  status: dead
+  email: tester2@email.com
+  password_digest: <%= BCrypt::Password.create('tpass2') %>
\ No newline at end of file
diff --git a/test/models/post_test.rb b/test/models/post_test.rb
new file mode 100644
index 0000000..ff155c4
--- /dev/null
+++ b/test/models/post_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class PostTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end
diff --git a/test/models/tag_test.rb b/test/models/tag_test.rb
new file mode 100644
index 0000000..1846cdb
--- /dev/null
+++ b/test/models/tag_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class TagTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end
diff --git a/test/models/tagging_test.rb b/test/models/tagging_test.rb
new file mode 100644
index 0000000..cb5040f
--- /dev/null
+++ b/test/models/tagging_test.rb
@@ -0,0 +1,7 @@
+require "test_helper"
+
+class TaggingTest < ActiveSupport::TestCase
+  # test "the truth" do
+  #   assert true
+  # end
+end