diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..b260680
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,15 @@
+# Build outputs produced by iterator_gdi.cmd / local Win32 toolchains
+*.exe
+*.obj
+*.pdb
+*.ilk
+
+# Runtime state and exports are local artifacts by default (see README.md)
+state/
+exports/
+
+# Editor/OS noise
+.vs/
+*.user
+.DS_Store
+Thumbs.db
diff --git a/README.md b/README.md
index c8c9950..b6542d2 100644
--- a/README.md
+++ b/README.md
@@ -26,7 +26,7 @@ See [docs/usage.md](docs/usage.md).
 
 ## Source Sharing
 
-The source set is the C files, build script, README, and documentation. Runtime data and generated exports are local artifacts unless deliberately shared.
+The source set is the C files, build script, README, documentation, and repository hygiene files such as `.gitignore`. Runtime data and generated exports are local artifacts unless deliberately shared.
 
 ## Generated Local Files