diff --git a/development.md b/development.md
new file mode 100644
index 0000000..b0299dd
--- /dev/null
+++ b/development.md
@@ -0,0 +1,38 @@
+# Development guide
+
+This project uses React framework with Typescript.
+It uses Webpack to manage module bundles and assets.
+
+## Project structure
+
+All high-level development configurations (e.g. typescript, babel, and eslint) are in their own dedicated files in project root.
+
+The project has a `pre-commit` hook that prevents committing changes that violate typing and linting configs.
+To check if the code passes the checks, run `npm run lint` and `npx tsc`. Running `npm run lint:fix` will try to fix the issues that can be resolved automatically.
+
+### Webpack
+
+All webpack configs are in `webpack.*.js`.
+
+Some dependencies like `maplibre` are bundled through their own entry in `entry` config to help with chunk size.
+
+Browser polyfills (`src/polyfill.js`), global styling of the app (`src/styles/main.scss`), and global config (`src/config.js`) are loaded directly using their own dedicated entry in webpack.
+
+The HTML entrypoint is `src/index.html`, which is loaded by `webpack-html-plugin`. Any global asset or remote resources (e.g. fonts) can be added here. The transpiled React code is injected into this file by webpack.
+
+`webpack.dev.js` is used with `start` script in `package.json` for development, and `webpack.prod.js` is used with `build` script.
+
+### Code
+
+Description of main files under `src` folder.
+
+| file/folder       | description                                                                                                                                                                                                                                            |
+|-------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
+| app.tsx           | The main entrypoint. It sets up the app, routing, default styling and themes, and some localizations.<br/>It also fetches some permanent data that is needed from the API in a `React.useEffect` hook.<br/>The rest of the data are fetches on-demand. |
+| routes.tsx        | Contains routes config. This config is used in `app.tsx`                                                                                                                                                                                               |
+| store/context.ts  | Uses React Context to store the data describing the state of the app, and functions for updating it.                                                                                                                                                   |
+| store/reducers.ts | Reducers are functions that update the state stored in the context with the data received from dispatchers.                                                                                                                                            |
+| store/states.ts   | The initial state of the app.                                                                                                                                                                                                                          |
+| store/api.ts      | Helper functions to interact with the API.                                                                                                                                                                                                             |
+| types/*           | Typescript types                                                                                                                                                                                                                                       |
+| components/*      | React components                                                                                                                                                                                                                                       |
diff --git a/src/components/Home/index.tsx b/src/components/Home/index.tsx
index 21f93b8..96c8654 100644
--- a/src/components/Home/index.tsx
+++ b/src/components/Home/index.tsx
@@ -281,7 +281,7 @@ const Home = (): JSX.Element => (
             }}
             variant="h2"
         >
-            The World&apos;s First Expedition of the Deep Sea
+            The World&apos;s First Exploration of the Deep Sea
         </Typography>
 
         <Typography
diff --git a/src/routes.tsx b/src/routes.tsx
index e870737..7fa01bd 100755
--- a/src/routes.tsx
+++ b/src/routes.tsx
@@ -6,6 +6,12 @@ import Loading from './components/Loading';
 
 const LazyHome = lazy(() => import('./components/Home'));
 
+/**
+ A mapping of routes to `RouteProps`.
+ The required property for each route is `element`, which must be a valid React component.
+
+ This mapping is used in `src/app.tsx` to set up all the routes.
+ * */
 const routes: { [key: string]: import('react-router-dom').RouteProps } = {
     '/': {
         element: (
diff --git a/src/store/contexts.ts b/src/store/contexts.ts
index eaefc35..3a27b78 100644
--- a/src/store/contexts.ts
+++ b/src/store/contexts.ts
@@ -1,3 +1,9 @@
+/**
+ * Various context storage that hold data and functions that can be used by different components.
+ * These are accessible in any place in the app that `React.useContext` can be used.
+ * For clarity, data and dispatchers (functions that update the state) are store in separate contexts.
+ */
+
 import React from 'react';
 
 import { dataStateInitialValue, filtersStateInitialValue } from './states';