This tutorial guides users through building an app with TypeScript, using the React.js and Next.js frameworks to query the Internet for current crypto-currency price data. The user is first required to set up their environment by installing Node.js, Yarn, and creating a new Next.js app. They then convert the existing JavaScript package to TypeScript, install dependencies, and create a configuration file. After that, they add a form to submit query parameters and write code to call the external API endpoint using async/await syntax. The user is also required to sign up for an API key from RapidAPI to access real-time data. The app uses a combination of HTTP GET and POST requests to retrieve data from the API. Finally, the user annotates variables and functions with types in a global TypeScript Declaration File to improve code readability and maintainability.