What is ChatGPT?

ChatGPT is OpenAI's flagship AI assistant, launched in November 2022. It grew faster than almost any consumer app before it, and it is still one of the most widely used AI assistants.

Current Models

ChatGPT runs on OpenAI's latest GPT model family. OpenAI ships a new flagship every few months, so the exact name changes often. The good news: you rarely need to know it. ChatGPT now hides most model names behind a simple picker. You choose how much effort you want, and ChatGPT routes your request to the right model.

For the current model names and which plan gets which, check OpenAI's models page. This course teaches how the pieces fit together, which stays true longer than any version number.

The flagship model

OpenAI's newest top model is the default on paid plans. It is the one people mean when they say "the latest GPT."

Feature	Details
Text	Strong writing, analysis, and coding
Vision	Can analyze images, charts, and documents
Voice	Real-time voice conversations
Reasoning	Can "think" longer on hard problems
Availability	Full access on paid tiers (Plus, Pro, Business)

The simplified picker: Instant, Thinking, and Pro

Instead of memorizing model numbers, you generally choose how much effort you want:

• Instant - Fast answers for everyday questions. This is the default for everyone. The free tier gets a fast model too, just with tight usage limits and no model picker.
• Thinking - The model reasons step by step before answering. Best for math, logic, planning, and careful coding. Available on paid tiers.
• Pro - The highest-effort reasoning mode, available on the Pro and business plans for the hardest problems.

You can also adjust how hard the model "thinks" with reasoning-effort settings on paid tiers.

Older models you may have heard of, such as GPT-4o, GPT-4.1 and the o-series, have been retired or replaced by newer GPT models.

Key Features

Custom GPTs

One of ChatGPT's most powerful features is the ability to create Custom GPTs—specialized assistants trained for specific tasks:

• No coding required - Build using natural language instructions
• Knowledge upload - Add documents, PDFs, or data the GPT can reference
• Custom actions - Connect to external APIs and services
• GPT Store - Browse and use GPTs created by others

Examples of popular Custom GPTs:

• Writing coaches for specific styles
• Coding assistants for particular languages
• Research helpers with specialized knowledge
• Creative tools for image generation prompts

Built-in Tools and Integrations

ChatGPT integrates with many tools and services:

• Web browsing - Search the internet for current information
• Image generation - Create images from text descriptions
• Code Interpreter (data analysis) - Run Python code, analyze data, create charts
• Connectors - Link tools like Google Drive, GitHub, and other services so ChatGPT can use your data

Memory

ChatGPT can remember information across conversations:

• User preferences and background
• Past projects and context
• Writing style preferences
• Frequently referenced information

This makes interactions more personalized and efficient over time.

Voice Mode

ChatGPT offers real-time voice conversations:

• Natural, flowing dialogue
• Multiple voice options
• Available on mobile apps
• Useful for hands-free assistance

What ChatGPT Does Well

ChatGPT excels in several areas:

Creative Writing

• Story generation and brainstorming
• Marketing copy and ad content
• Blog posts and articles
• Poetry and creative formats

Code Generation

• Writing code from descriptions
• Debugging existing code
• Explaining code functionality
• Converting between languages

Multimodal Tasks

• Analyzing images and screenshots
• Extracting text from photos
• Describing visual content
• Working with charts and graphs

Ecosystem Integration

• Custom GPTs for specialized tasks
• Plugin connectivity
• API access for developers
• Microsoft 365 Copilot integration

Limitations to Know

Every tool has limitations. ChatGPT's include:

• Knowledge cutoff - Training data has a cutoff date (though web browsing helps)
• Hallucinations - Can confidently state incorrect information
• Context limits - Long conversations may lose early context
• Consistency - May give different answers to the same question
• Sensitive topics - Sometimes overly cautious on legitimate questions

Key Takeaways

• ChatGPT runs on OpenAI's latest GPT models; you pick a mode (Instant, Thinking, Pro) rather than a model number
• Paid plans get the flagship model; the free tier gets a fast model with tighter usage limits
• Custom GPTs let you build specialized assistants without coding
• Strong ecosystem with image generation (built-in), voice, web browsing, and integrations
• Excels at creative writing, coding, multimodal tasks, and step-by-step reasoning (Thinking mode)
• Memory feature enables personalized, contextual conversations