Having established techniques for designing effective prompts, we now turn to the practical aspect of using these prompts within software applications. This chapter concentrates on interacting programmatically with Large Language Models (LLMs) through their Application Programming Interfaces (APIs). You will learn the necessary steps to connect your code to LLM services, send prompts, and handle the generated responses.

Specifically, this chapter covers:

• An overview of common LLM APIs and their functionalities.
• Methods for secure API authentication.
• Using Python to structure and send API requests.
• Understanding key request parameters like model selection and generation controls.
• Parsing and utilizing API responses within your application.
• Strategies for managing potential API errors and usage limits.
• Implementing streaming to receive responses incrementally.

Through practical examples, including building a basic Q&A application, you will gain hands-on experience in making API calls and processing the results, forming a foundation for building LLM-integrated software.