diff --git a/DESIGN.md b/DESIGN.md
index 44e2dde8..c5a69113 100644
--- a/DESIGN.md
+++ b/DESIGN.md
@@ -4,6 +4,15 @@
 
 ### libsysprof-2
 
+This library provides various profiling infrastructure for Sysprof.
+This includes the core interfaces for data sources, capture readers
+and writers, and the SpProfiler implementation. It also includes
+the SpProfile interface and its various implementations, such as
+SpCallgraphProfile. If you need a no-frills library to perform
+captures this is all you need.
+
+### libsysprof-ui-2
+
 This library provides various UI components and profiling tools as a library.
 It is intended to be used from IDEs such as GNOME Builder.