diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index a7ee5307c..1f73b1e58 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -20,7 +20,7 @@ You are welcome to contribute to this project. Here are the guidelines we try to
     * [Installing Grunt](#installing-grunt)
   * [Configuring The Server](#configuring-the-server)
   * [Starting The Server](#starting-the-server)
-  * [Building Project](#building-project)
+  * [Building the Project](#building-the-project)
 * [Coding](#coding)
 * [Running Tests](#running-tests)
   * [Functional Tests](#functional-tests)
@@ -333,7 +333,14 @@ make start
 
 You should now have a local instance of the site running at `http://localhost:5000/`. Please [file bugs](https://github.com/webcompat/webcompat.com/issues/new) if something went wrong!
 
-### Building Project
+### Building the Project
+
+You need to build the project before serving it from a webserver will work, and after certain kinds of changes are made.
+
+* CSS: a build will run cssnext, combine custom media queries, and concat all source files into webcompat.dev.css. You'll need to re-build the CSS to see any changes, so it's recommended to use a watch task (see `make watch` or `grunt watch`).
+* JS: a build will run eslint, minify and concat source files.
+* HTML templates: the changes should be served from disk without the need for rebuilding
+* Python: the Flask local server will detect changes and restart automatically. No need to re-build.
 
 You can build the entire project (CSS and JavaScript files and optimize images) by executing this command on Mac/Linux:
 
@@ -355,6 +362,7 @@ grunt
  make watch
  ```
 
+By default, a build will *not* optimize images (which is done before deploys). If you'd like to do that, you can run `grunt imagemin`.
 
 ## Running Tests
 
diff --git a/Gruntfile.js b/Gruntfile.js
index 90de471a3..d77064b24 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -23,6 +23,11 @@ module.exports = function(grunt) {
 
   // Default task.
   grunt.registerTask('default', [
+    'checkDependencies', 'eslint', 'concat', 'uglify','cssnext', 'cssmin'
+  ]);
+
+  // Task used before doing a deploy (same as default, but does image optimization)
+  grunt.registerTask('deploy', [
     'checkDependencies', 'eslint', 'concat', 'uglify','cssnext', 'cssmin', 'imagemin'
   ]);
 };