The tutorial extends a Flask web application with APIs to programmatically gather or distribute data. The API creation process is simplified by creating a set of routes that receive requests and return useful data. An example is created for the "I Love Dogs" site, which has sections organized by topics. A RESTful API endpoint is built to return a list of resources related to a specified topic. The API uses PyYaml to read in .yml files and convert them into Python dictionaries. To handle malicious users and invalid topic types, error handling mechanisms are implemented, such as returning a 404 response when the requested data cannot be found. The tutorial concludes with the final API endpoints and testing.