diff --git a/Doc/reference/import.rst b/Doc/reference/import.rst
index 881e0ae..45d4172 100644
--- a/Doc/reference/import.rst
+++ b/Doc/reference/import.rst
@@ -675,6 +675,33 @@
    :meth:`~importlib.abc.Loader.module_repr` method, if defined, before
    trying either approach described above.  However, the method is deprecated.
 
+.. _pyc-invalidation:
+
+Cached bytecode invalidation
+----------------------------
+
+Before Python loads cached bytecode from ``.pyc`` file, it checks whether the
+cache is up-to-date with the source ``.py`` file. By default, Python does this
+by storing the source's last-modified timestamp and size in the cache file when
+writing it. At runtime, the import system then validates the cache file by
+checking the stored metadata in the cache file against at source's
+metadata.
+
+Python also supports "hash-based" cache files, which store a hash of the source
+file's contents rather than its metadata. There are two variants of hash-based
+``.pyc`` files: checked and unchecked. For checked hash-based ``.pyc`` files,
+Python validates the cache file by hashing the source file and comparing the
+resulting hash with the hash in the cache file. If a checked hash-based cache
+file is found to be invalid, Python regenerates it and writes a new checked
+hash-based cache file. For unchecked hash-based ``.pyc`` files, Python simply
+assumes the cache file is valid if it exists. Hash-based ``.pyc`` files
+validation behavior may be overridden with the :option:`--check-hash-based-pycs`
+flag.
+
+.. versionchanged:: 3.7
+   Added hash-based ``.pyc`` files. Previously, Python only supported
+   timestamp-based invalidation of bytecode caches.
+
 
 The Path Based Finder
 =====================