diff --git a/README.md b/README.md
index a7b24b2..07f2605 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,7 @@
 # WS3_annual_most_used_survey_blocklist
-The website w3tech publishes surveys on most used internet technology including advertising, tagging and tracking services.
+The website w3tech publishes surveys on most used internet technology including advertising, tagging and traffic analysis services:
+https://w3techs.com/technologies/overview/advertising/all
+https://w3techs.com/technologies/overview/traffic_analysis/all
+https://w3techs.com/technologies/overview/tag_manager/all
+
+This small but effective list is simply based on the annual surveys of W3C technology