Models & GPTs Beginner

OpenAI offers a family of models optimized for different tasks. Understanding the differences helps you choose the right model for each situation, saving time and cost. This lesson also covers Custom GPTs and the GPT Store.

Available Models

GPT-4o - Flagship Multimodal Model

GPT-4o ("omni") is OpenAI's flagship model. It natively handles text, vision, and audio with a single model architecture. It is faster and cheaper than GPT-4 Turbo while delivering similar or better performance across most benchmarks.

• Context window: 128K tokens
• Multimodal: Text, images, and audio input/output
• Best for: General-purpose tasks, conversational AI, code generation, content creation
• Speed: 2x faster than GPT-4 Turbo

GPT-4o mini - Fast and Affordable

GPT-4o mini is a smaller, faster, and significantly cheaper version of GPT-4o. It is designed for tasks that need quick responses and high throughput without requiring the full capability of GPT-4o.

• Context window: 128K tokens
• Best for: Simple tasks, high-volume applications, cost-sensitive use cases
• Pricing: ~60x cheaper than GPT-4o per token
• Free tier: Available to all ChatGPT users

o1 and o3 - Reasoning Models

The o-series models use internal chain-of-thought reasoning before producing a response. They "think" through problems step by step, making them significantly better at complex math, science, coding challenges, and logical reasoning.

• o1: First reasoning model. Excels at math competitions, PhD-level science questions, and complex coding
• o3: Next-generation reasoning model with improved performance and efficiency
• Trade-off: Slower response times due to internal reasoning, higher cost per query
• Best for: Complex problem solving, scientific reasoning, competitive programming

GPT-4 Turbo

GPT-4 Turbo was the previous-generation flagship model with a 128K context window. While still available via the API, it has been largely superseded by GPT-4o for most use cases.

Model Comparison

Custom GPTs

Custom GPTs are specialized versions of ChatGPT that anyone can create without writing code. Each GPT can have:

• Custom instructions: A system prompt that defines the GPT's personality, expertise, and behavior
• Knowledge files: Upload documents that the GPT can reference when answering questions
• API Actions: Connect to external APIs so the GPT can fetch data or trigger actions
• Tools: Enable browsing, DALL-E image generation, or Code Interpreter

Creating a Custom GPT

1. Open the GPT Builder

   Click your profile icon in ChatGPT, then select "My GPTs" > "Create a GPT". The GPT Builder opens in a split-screen view.

2. Describe your GPT

   Tell the builder what your GPT should do in natural language. For example: "Create a GPT that helps users write professional LinkedIn posts."

3. Configure settings

   Switch to the "Configure" tab to fine-tune the name, description, instructions, conversation starters, knowledge files, and capabilities.

4. Test and iterate

   Use the preview panel on the right to test your GPT. Adjust instructions until it behaves as desired.

5. Publish

   Choose to keep your GPT private, share via link, or publish to the GPT Store for anyone to find.

# LinkedIn Post Writer GPT

You are a professional LinkedIn content writer.

Your role:
- Help users create engaging LinkedIn posts
- Use a professional but conversational tone
- Include relevant hashtags (3-5 per post)
- Keep posts between 150-300 words
- Suggest a hook for the first line
- Format with line breaks for readability

Rules:
- Never use clickbait or misleading content
- Always ask about the target audience
- Suggest a call-to-action at the end
- Offer 2-3 variations when possible

GPT Store

The GPT Store is a marketplace where users can discover and use Custom GPTs created by the community and verified builders. GPTs are organized into categories including:

When to Use Which Model