Flask is a lightweight Python web framework used to build web applications, and it's ideal for developers new to Python. To start building Flask apps with Flask, one needs to install the necessary libraries such as Flask, Requests, and Twilio's Python library. A module called spotify.py was created to interact with Spotify's search API, which returns a JSON response containing the URL associated with the preview of the first track in the search. The code also sets up a Twilio account, allows users to text a phone number to provide a search query, and builds a Flask app using the Twilio REST API that responds to SMS messages by playing a clip of the searched song from Spotify.