What is ChatGPT?
ChatGPT is OpenAI's flagship AI assistant, launched in November 2022. It quickly became the fastest-growing consumer application in history, reaching 100 million users in just two months. Today, it remains the most widely used AI assistant globally.
Current Models
As of mid-2026, ChatGPT runs on the GPT-5 family. OpenAI has simplified the model picker so most people no longer choose raw model names—instead you pick a mode and ChatGPT routes your request to the right underlying model.
GPT-5.5 (flagship)
GPT-5.5 is OpenAI's most capable model. It launched in late April 2026, replacing GPT-5.4, and rolled out as ChatGPT's default model across all plans in May 2026.
| 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 | 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, including the free tier (which gets GPT-5.5 Instant 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 (GPT-5.5 Pro), 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—GPT-4o, GPT-4.1, and the o1/o3/o4-mini reasoning series—were retired in early 2026 and folded into the GPT-5 family.
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 the GPT-5 family; you pick a mode (Instant, Thinking, Pro) rather than a model number
- GPT-5.5 is the flagship; since May 2026 even the free tier defaults to GPT-5.5 Instant, just 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