Okay, so I identified the two items that we need to build to make this all happen: the JSON manifest file and the service worker! Easy, right? Actually, it's even easier than that. You see, Create React App will populate a JSON manifest file for us as part of our project creation by default! That means we have already completed this step! Let's celebrate, go home, and kick off our shoes, because we're all done now, right?

Well, sort of. We should take a look at that default manifest file because it's very unlikely that we want our fancy TodoList project to be called "Create React App Sample". Let's take a look at the manifest file, located in public/manifest.json:

{
 "short_name": "React App",
 "name": "Create React App Sample",
 "icons": [
 {
 "src": "favicon.ico",
 "sizes": "64x64 32x32 24x24 16x16",
 "type": "image/x-icon"
 }
 ],
 "start_url": ".",
 "display": "standalone",
 "theme_color": "#000000",
 "background_color": "#ffffff"
}

Some of these keys are pretty self-explanatory or at least have a little bit of information that you can infer from them as to what they accomplish. Some of the other keys, though, might be a little stranger. For example, what does "start_url" mean? What are the different options we can pick for display? What's a "theme_color" or "background_color"? Aren't those just decided by the CSS of our application?

Not quite. In fact, let's dive super deep into this world of JSON manifest files and turn it into something more useful!