diff --git a/README.md b/README.md
index 6cef86a..c9bb66b 100644
--- a/README.md
+++ b/README.md
@@ -23,10 +23,18 @@ with vcr.use_cassette('fixtures/vcr_cassettes/synopsis.yaml'):
     assert 'Example Domains' in response
 ```
 
+Run this test once, and VCR.py will record the http request to
+fixtures/vcr_cassettes/synopsis.yml. Run it again, and VCR.py will replay the
+response from iana.org when the http request is made. This test is now fast (no
+real HTTP requests are made anymore), deterministic (the test will continue to
+pass, even if you are offline, or iana.org goes down for maintenance) and
+accurate (the response will contain the same headers and body you get from a
+real request).
+
 ##Ruby VCR compatibility
 I'm not trying to match the format of the YAML files.  Cassettes generated by
-Ruby's VCR are not compatible with VCR.py.  The API is similar but I don't have
-nearly as many features
+Ruby's VCR are not compatible with VCR.py.  The API is similar but VCR.py
+doesn't have nearly as many features.
 
 ##Similar libraries in Python
 Neither of these really implement the API I want, but I have cribbed some code