diff --git a/README.md b/README.md
index 1e64955..af59e42 100644
--- a/README.md
+++ b/README.md
@@ -3,3 +3,71 @@
 [![NPM version](http://img.shields.io/npm/v/create-index.svg?style=flat-square)](https://www.npmjs.org/package/create-index)
 [![Travis build status](http://img.shields.io/travis/gajus/create-index/master.svg?style=flat-square)](https://travis-ci.org/gajus/create-index)
 [![js-canonical-style](https://img.shields.io/badge/code%20style-canonical-blue.svg?style=flat-square)](https://github.com/gajus/canonical)
+
+`create-index` program creates ES6 `./index.js` file in target directories that imports and exports all sibling files and directories.
+
+## Implementation
+
+`create-index` program will look into the target directory.
+
+If there is no `./index.js`, it will create a new file, e.g.
+
+```js
+'create index';
+```
+
+Created index file must start with `'create index';\n\n`. This is used to make sure that `create-index` does not accidentally overwrite your local files.
+
+If there are sibling files, index file will import them and export, e.g.
+
+```sh
+children-directories-and-files git:(master) ✗ ls -lah
+total 0
+drwxr-xr-x   5 gajus  staff   170B  6 Jan 15:39 .
+drwxr-xr-x  10 gajus  staff   340B  6 Jan 15:53 ..
+drwxr-xr-x   2 gajus  staff    68B  6 Jan 15:29 bar
+drwxr-xr-x   2 gajus  staff    68B  6 Jan 15:29 foo
+-rw-r--r--   1 gajus  staff     0B  6 Jan 15:29 foo.js
+```
+
+Given the above directory contents, index will be:
+
+```js
+'create index';
+
+import bar from './bar';
+import foo from './foo.js';
+
+export {
+    bar,
+    foo
+};
+```
+
+If there are files with the same name as directories in the same directory, file will take precedence.
+
+Directories that do not have `./index.js` in themselves will be excluded.
+
+## Using CLI Program
+
+```sh
+create-index ./directory1 ./directory2 ./directory3 ...
+```
+
+## Using `create-index` Programmatically
+
+```js
+import {
+    writeIndex
+} from 'create-index';
+
+/**
+ * @type {Function}
+ * @param {Array<string>} directoryPaths
+ * @throws {Error} Directory "..." does not exist.
+ * @throws {Error} "..." is not a directory.
+ * @throws {Error} "..." unsafe index.
+ * @returns {boolean}
+ */
+writeIndex;
+```
diff --git a/package.json b/package.json
index dde3e02..fb31d95 100644
--- a/package.json
+++ b/package.json
@@ -1,8 +1,9 @@
 {
   "name": "create-index",
-  "description": "",
+  "description": "Creates ES6 ./index.js file in target directories that imports and exports all sibling files and directories.",
   "version": "0.0.0",
   "main": "./dist/index.js",
+  "bin": "./dist/bin/create-index.js",
   "repository": {
     "type": "git",
     "url": "https://github.com/gajus/create-index"
@@ -29,6 +30,11 @@
     "watch-build": "npm run pragmatist watch-build"
   },
   "devDependencies": {
-    "pragmatist": "^2.3.67"
+    "chai": "^3.4.1",
+    "pragmatist": "^2.3.70"
+  },
+  "dependencies": {
+    "lodash": "^3.10.1",
+    "yargs": "^3.31.0"
   }
 }
diff --git a/src/index.js b/src/index.js
index e69de29..43f759e 100644
--- a/src/index.js
+++ b/src/index.js
@@ -0,0 +1,14 @@
+'create index';
+
+import createIndexCode from './createIndexCode.js';
+import readDirectory from './readDirectory.js';
+import validateTargetDirectory from './validateTargetDirectory.js';
+import writeIndex from './writeIndex.js';
+
+export {
+    createIndexCode,
+    readDirectory,
+    validateTargetDirectory,
+    writeIndex
+};
+