modified: index.mdx

	modified:   part1/simple_detector.md

src/docs/index.mdx

@@ -15,9 +15,9 @@ together to get some results and serve as a jumping off point for further develo
 
 - [Quick start](getting-started/quickstart) - Start here to download software and configure your development environment.
 
-- [Part 1](part1/simple_detector.md) - An introduction to the detector description starting with a simple detector. 
+- [Part 1](part1/simple_detector.md) - An introduction to using compact detector descriptions, running Geant4 simulation, and processing the data using DD4hep hooks. 
 
-- [Part 2](part2/adding_detectors.md) - This tutorial shows how to add new parameterized detectors to a library of generic detectors (NPdet).
+- [Part 2](part2/adding_detectors.md) - A basic example of how to create new detector geometries, add new sensitive detector constructors, and extend existing detector libraries.
 
 
 ## Background Discussion

src/docs/part1/simple_detector.md

@@ -109,8 +109,9 @@ world_z                        =    10000.000 = 10*world_side
 
 This is very useful with a good subsystem naming convention.
 
+## Running Geant4 simulation
 
-## Run the geant4 simulation
+`npsim` is a clone of DD4hep's `ddsim` but has a different output plugin. 
 
 ```bash
 npsim  --runType run  --enableG4GPS \