diff --git a/common_tags.py b/common_tags.py
new file mode 100644
index 0000000..da631f8
--- /dev/null
+++ b/common_tags.py
@@ -0,0 +1,11 @@
+from __future__ import annotations
+
+
+def find_common_tags(articles: list[dict[str, list[str]]]) -> set[str]:
+    if not articles:
+        return set()
+
+    common_tags = articles[0]["tags"]
+    for article in articles[1:]:
+        common_tags = [tag for tag in common_tags if tag in article["tags"]]
+    return set(common_tags)
\ No newline at end of file