diff --git a/docs/index.rst b/docs/index.rst
index 7c7c8bc..79fa301 100644
--- a/docs/index.rst
+++ b/docs/index.rst
@@ -1,27 +1,36 @@
 .. _swh-search:
 
 Software Heritage - search service
 ==================================
 
 The SWH search service, or swh-search, stores a partial copy of
 the |swh| archive.
 It is similar to swh-storage in what it contains,
 but provides different ways to query it: while swh-storage is mostly
 a key-value store that returns an object from a primary key,
 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
    :caption: Contents:
 
    cli
 
 Reference Documentation
 -----------------------
 
 .. toctree::
    :maxdepth: 2
 
    /apidoc/swh.search