This document provides an overview of building a simple to-do list application in Rails over the course of four days. Day 1 covers generating the Rails application, setting up the database and web server, and generating a scaffold for the categories table. Day 2 analyzes the generated scaffold code and customizes it. Day 3 adds an items table, validations between tables, and more scaffolding. Day 4 links notes to items, adds navigation, and downloads the application. The goal is to demonstrate how to build a basic application with Rails and identify resources to continue learning.