ChatGPT is OpenAI’s flagship AI assistant, now running on the newly released GPT-5.6 family, which comes in three tiers: Sol (the top-tier flagship for the toughest reasoning, coding, and agentic work), Terra (a balanced everyday option), and Luna (the fastest and cheapest of the bunch). ChatGPT is genuinely useful across a huge range of tasks – writing, coding, research, spreadsheets, presentations, image generation, browsing the web for you, and even taking over your screen to inspect and fix its own output before handing it back.
To use it, you just type a prompt into the chat box (or hand it a document, a Slack thread, spreadsheet, etc) and it takes it from there, and for harder problems you can bump up the reasoning effort or turn on “ultra” mode, which runs multiple agents in parallel to tackle a task faster. There’s a free tier through ChatGPT Work that gives access to the Terra model, while Plus, Pro, Business, and Enterprise subscribers unlock the full Sol model along with higher effort settings and the multi-agent ultra mode. Developers can also pull all three models straight from the API, priced per million tokens depending on which tier you choose.
