diff --git a/docs/index.rst b/docs/index.rst
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -11,6 +11,15 @@
 swh-search is focused on reverse indices, to allow finding objects that
 match some criteria; for example full-text search.
 
+It is currently based on Elasticsearch, allowing full-text search on both
+URLs (using a ``search_as_you_type`` index) and on intrinsic metadata of
+their head revision in CodeMeta_ format.
+
+It is kept in sync with :ref:`the main SWH storage <swh-storage>` via
+:ref:`the SWH journal <swh-journal>`.
+
+.. _CodeMeta: https://codemeta.github.io/
+
 
 .. toctree::
    :maxdepth: 2