diff --git a/lib/feed_reader/feed.ex b/lib/feed_reader/feed.ex
new file mode 100644
index 0000000..4e529d8
--- /dev/null
+++ b/lib/feed_reader/feed.ex
@@ -0,0 +1,26 @@
+defmodule FeedReader.Feed do
+  @moduledoc """
+  Normalized metadata for a feed.
+
+  Extension metadata is keyed by namespace URI. Format implementations control
+  which bounded extension values are retained.
+  """
+
+  @type t :: %__MODULE__{
+          title: String.t() | nil,
+          description: String.t() | nil,
+          feed_url: String.t() | nil,
+          html_url: String.t() | nil,
+          type: :rss | :atom | :rdf,
+          categories: [String.t()],
+          extensions: %{optional(String.t()) => map()}
+        }
+
+  defstruct title: nil,
+            description: nil,
+            feed_url: nil,
+            html_url: nil,
+            type: nil,
+            categories: [],
+            extensions: %{}
+end
diff --git a/lib/feed_reader/item.ex b/lib/feed_reader/item.ex
new file mode 100644
index 0000000..7e979b1
--- /dev/null
+++ b/lib/feed_reader/item.ex
@@ -0,0 +1,27 @@
+defmodule FeedReader.Item do
+  @moduledoc "A normalized item delivered by a feed parser."
+
+  @type t :: %__MODULE__{
+          uuid: String.t() | nil,
+          title: String.t() | nil,
+          content_full: String.t() | nil,
+          content_summary: String.t() | nil,
+          language: atom() | nil,
+          published_at: DateTime.t() | nil,
+          canonical_url: String.t() | nil,
+          alternate: map(),
+          author: String.t() | nil,
+          extensions: %{optional(String.t()) => map()}
+        }
+
+  defstruct uuid: nil,
+            title: nil,
+            content_full: nil,
+            content_summary: nil,
+            language: nil,
+            published_at: nil,
+            canonical_url: nil,
+            alternate: %{},
+            author: nil,
+            extensions: %{}
+end