diff --git a/scripts/build.js b/scripts/build.js
index 2b9c46b..44fdea7 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -3,6 +3,8 @@
 // Do this as the first thing so that any code reading it knows the right env.
 process.env.NODE_ENV = 'production';
 
+// Use dynamic server data in production by inserting a token that will be
+// replaced when the HTML page is served.
 process.env.REACT_APP_SERVER_DATA = '__SERVER_DATA__';
 
 // Load environment variables from .env file. Suppress warnings using silent
diff --git a/scripts/start.js b/scripts/start.js
index 1f0b851..b42185a 100644
--- a/scripts/start.js
+++ b/scripts/start.js
@@ -2,6 +2,7 @@
 
 process.env.NODE_ENV = 'development';
 
+// Use static server data in development.
 process.env.REACT_APP_SERVER_DATA = JSON.stringify(require('../server/dev-data'))
 
 // Load environment variables from .env file. Suppress warnings using silent
diff --git a/server/index.js b/server/index.js
index 12d67da..93fc846 100644
--- a/server/index.js
+++ b/server/index.js
@@ -19,6 +19,8 @@ const sendHomePage = (publicDir) => {
       } else {
         res.set('Cache-Control', 'public, max-age=60')
         res.send(
+          // Replace the __SERVER_DATA__ token that was added to the
+          // HTML file in the build process (see scripts/build.js).
           html.replace('__SERVER_DATA__', JSON.stringify({
             cloudflareStats: stats
           }))