> ## Documentation Index
> Fetch the complete documentation index at: https://notes.kodekloud.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Section Intro

> This comprehensive guide teaches building an interactive chatbot using OpenAI’s GPT-3.5 and GPT-4 models for customer service applications.

Welcome to this comprehensive guide on building an interactive chatbot powered by OpenAI’s GPT-3.5 and GPT-4 models. In this tutorial, you’ll learn how to:

* Craft effective prompts for both word-based and conversational APIs
* Manage conversation history to maintain context
* Assemble building blocks for a responsive customer-service chatbot
* Deploy a sample chatbot for a fictional fast-food burger restaurant

By the end of this lesson, you’ll have a solid understanding of how to integrate OpenAI’s chat completions into your applications and deliver a seamless conversational experience.

<Callout icon="lightbulb" color="#1CB2FE">
  Make sure you have an active OpenAI API key. You can sign up at [OpenAI](https://platform.openai.com/signup).
</Callout>

## Word Completion vs. Chat Completion

| Feature            | Word Completion                   | Chat Completion                                   |
| ------------------ | --------------------------------- | ------------------------------------------------- |
| API Endpoint       | `/v1/completions`                 | `/v1/chat/completions`                            |
| Input Format       | Plain prompt string               | Array of structured messages                      |
| Best Use Cases     | Short text generation, code fixes | Stateful conversations, multi-turn dialogues      |
| Model Examples     | `text-davinci-003`                | `gpt-3.5-turbo`, `gpt-4`                          |
| Context Management | Limited (token-based)             | Full message history, system/user/assistant roles |

## What You’ll Build

1. **Prompt Engineering**: Learn how to frame user requests for accurate responses.
2. **Context Storage**: Implement a history buffer to pass previous messages to the API.
3. **Chat Loop**: Create an interactive loop to send and receive messages.
4. **Fast-Food Bot**: Deploy a customer-service chatbot that takes orders, answers FAQs, and handles errors.

Let’s dive into the details!

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