diff --git a/common_tags.py b/common_tags.py
new file mode 100644
index 0000000..8cbb836
--- /dev/null
+++ b/common_tags.py
@@ -0,0 +1,13 @@
+from __future__ import annotations
+
+
+def find_common_tags(articles: list[dict[str, list[str]]]) -> set[str]:
+    if not articles:
+        return set()
+
+    # Using set intersection to find common tags
+    common_tags = set(articles[0]["tags"])
+    for article in articles[1:]:
+        common_tags.intersection_update(article["tags"])
+
+    return common_tags