This segment explains how to define and use path parameters in FastAPI to retrieve specific resources (posts in this case) using a GET request. The speaker clearly demonstrates how the URL structure (`/posts/{id}`) allows the user to specify the ID of the desired post, which is then automatically extracted by FastAPI and made available to the function. The explanation of path parameters as a key concept in API design is valuable for understanding RESTful API principles. This tutorial demonstrates building a FastAPI application to manage posts. It covers retrieving a single post using a path parameter (`/posts/{id}`). The path parameter, initially a string, is validated and converted to an integer using FastAPI's type hinting, preventing errors from invalid input. A `find_post` function retrieves the post from a list (later to be replaced with database interaction). Error handling is improved by leveraging FastAPI's built-in validation, providing user-friendly error messages. This segment showcases a common issue when working with path parameters: type mismatch. The speaker encounters an error because the path parameter (ID) is received as a string, while the application expects an integer. The debugging process and the solution (explicit type conversion using `int()`) are clearly shown. The importance of data validation is highlighted, demonstrating how FastAPI's built-in validation mechanisms can prevent such errors and provide more informative error messages to the user.