diff --git a/docs/web_client.md b/docs/web_client.md
index 3dc67819fc280a87cb3d154c0987ea185d205389..4d86b79330070e5b283e91d57ab59348c2dee52a 100644
--- a/docs/web_client.md
+++ b/docs/web_client.md
@@ -30,6 +30,9 @@ You should land on the following page.
 You can then select the dataset of your choice to search into.
 For an example, try the **VIPERS-W1 (DR2)** dataset.
 
+**Note**: datasets are grouped into families. Families of datasets can be defined as related datasets of common interest.
+For instance, on the previous picture the *Default dataset family*.
+
 ### Adding criteria
 
 A form should now appear in front of you.