What Is ChatGPT? How It Works, Plans and What You Can Do With It

ChatGPT is an AI assistant made by OpenAI that understands and writes text, answers questions, analyzes files and images, creates pictures, talks by voice and, through ChatGPT Work, carries out multi-step tasks for you. It runs on OpenAI’s GPT family of large language models, currently GPT-5.6 and GPT-6, and it is free to use at chatgpt.com and in the mobile and desktop apps, with paid plans from $8 a month. With more than 1 billion weekly users, it is the most widely used AI tool in the world.

This guide explains what ChatGPT is in plain English: how it works, what it can and cannot do, the plans and models, everyday examples, privacy basics and how it compares with Claude, Gemini and Google Search. If you want step-by-step instructions, see our companion guide on how to use ChatGPT.

What ChatGPT is, in simple terms

Think of ChatGPT as a very well-read assistant you talk to in plain language. You type or say what you want, such as “explain GST input tax credit simply” or “turn these notes into a polite email”, and it replies in seconds. You can keep the conversation going, ask it to change the answer, or give it files and photos to work with.

“Chat” refers to the conversational interface. “GPT” stands for Generative Pre-trained Transformer, the type of AI model behind it. The model is “generative” because it creates new text, “pre-trained” because it learned from large amounts of text before you ever use it, and a “transformer” is the neural network design that makes this possible. Our explainer on what a large language model is goes deeper.

How ChatGPT works

1. Training. OpenAI trained its models on a very large collection of text, learning patterns of language, facts and reasoning. It then refined them with human feedback so answers are more helpful and safer.
2. Your prompt becomes tokens. When you send a message, it is split into small pieces called tokens. Our guide to tokens in AI explains this.
3. Prediction. The model predicts the most likely next token again and again to build a response. Reasoning models “think” through steps before answering.
4. Tools. For some questions ChatGPT searches the web, runs Python code on your data, reads your files or creates an image, then uses the results in its answer.
5. Memory and context. It considers the conversation so far, and, if you allow it, saved memories about your preferences.

Because it predicts likely text rather than looking up a single truth, ChatGPT can sound confident and still be wrong. These errors are called hallucinations.

What can ChatGPT do?

For ready-made ideas, browse our list of the best ChatGPT prompts, and for agent-style tasks see how to use ChatGPT Work.

What ChatGPT cannot do well

• Guarantee accuracy. It can invent facts, numbers or citations. Verify anything important.
• Replace professionals. It is not a doctor, lawyer or financial adviser.
• Know everything recent. Models have a training cutoff; web search helps but is not perfect.
• Act without access. It can only use the files, apps and websites you connect or allow.
• Keep secrets by default. On personal plans, chats can be used to improve models unless you turn that off.

ChatGPT plans and models

OpenAI’s model tiers are named Luna (fast and economical), Sol (balanced) and Astra (most capable). Our GPT-6 models explainer, ChatGPT pricing guide and Free vs Plus comparison cover the details. Official plans are on the ChatGPT pricing page.

Everyday ways people use ChatGPT

• Students: explanations, practice questions and feedback on essays. See our ChatGPT prompts for students.
• Small businesses: customer replies, social posts, product descriptions and simple data analysis.
• Job seekers: résumé edits, cover emails and interview practice.
• Professionals: meeting summaries, report drafts, spreadsheet formulas and research.
• Families: trip planning, recipe ideas and help with forms written in difficult language.

How to get started with ChatGPT in 5 minutes

1. Open ChatGPT. Go to chatgpt.com or install the official ChatGPT app from the App Store or Play Store. Check that the developer is OpenAI, since copycat apps exist.
2. Sign up or log in. Use an email, Google, Microsoft or Apple account. You can try some features without an account, but signing in saves your history.
3. Ask a real question. Start with something you need today, such as “Write a short, polite message asking my landlord to fix the water heater.”
4. Refine the answer. Reply with changes: “make it shorter”, “more formal”, “add a deadline of Friday”. This back-and-forth is where ChatGPT shines.
5. Try a file or photo. Upload a PDF, a screenshot or a photo of a document and ask for a summary or explanation.
6. Adjust privacy settings. In Settings, review Data Controls and memory so ChatGPT works the way you are comfortable with.

Is ChatGPT safe and private?

ChatGPT is generally safe for everyday use with sensible settings. On personal plans, turn off “Improve the model for everyone” in Data Controls if you do not want chats used for training, use Temporary Chat for one-off sensitive questions, and turn on multi-factor authentication. Never paste passwords, ID numbers or confidential client data. Business, Enterprise and Edu plans do not train on workspace data by default. Our full guide on whether ChatGPT is safe walks through every setting, and OpenAI’s data controls FAQ explains the options.

ChatGPT vs other AI tools

See our comparisons of ChatGPT vs Google Search, ChatGPT vs Claude, ChatGPT vs Gemini and our list of ChatGPT alternatives.

A short history of ChatGPT

• November 2022: ChatGPT launches and reaches 100 million monthly users in about two months.
• August 2025: the low-cost Go plan launches in India first.
• January 2026: Go goes worldwide, and OpenAI starts testing ads on the free US tier.
• July 2026: ChatGPT Work launches for multi-step tasks.
• August 2026: ChatGPT passes 1 billion weekly users.
• September 2026: GPT-6 arrives in Work and Codex, and DevDay adds always-on dots agents.

Read our recap of OpenAI DevDay 2026 for the latest features.

Frequently asked questions

The bottom line

ChatGPT is a general-purpose AI assistant that has become, for many people, the first place they go to write, learn, research and get work done. Start with the free plan, learn a few good prompting habits, and upgrade only when you hit limits. Treat its answers as a strong starting point, not the final word. Features and plans change quickly, so check OpenAI’s pricing and help pages for the latest details. Ready to try it? Follow our step-by-step guide on how to use ChatGPT, and if it ever stops responding, see ChatGPT not working fixes.

Related reading: what generative AI is.