diff --git a/server/notes.txt b/server/notes.txt
index 2df26d3..dd5fd08 100644
--- a/server/notes.txt
+++ b/server/notes.txt
@@ -21,4 +21,7 @@ product vs custom
 
 ARR/IRR
 
+ARR = accounting rate of return / annual recurring revenue = annual predicted net profit / initial investment
+IRR = internal rate of return
+
 suivi engagement (risk, event, deps, done vs planned)