What Is ChatGPT? A Plain English Guide

ChatGPT launched in late 2022 and became one of the fastest-adopted software products in history. Millions of people who had never consciously used an AI tool before started asking it questions, getting it to write things, and integrating it into their daily work.

If you've heard a lot about it but want a clear explanation of what it actually is and how it works, this guide covers everything you need to know.

The Short Version

ChatGPT is a conversational AI assistant made by OpenAI. You type a message, it responds. You can ask it questions, ask it to write things, explain concepts, summarise documents, write code, brainstorm ideas, or have an extended back-and-forth conversation.

The underlying technology is a large language model (LLM) — a type of AI trained on enormous amounts of text that can generate coherent, contextually appropriate responses to almost any input.

Who Makes It?

ChatGPT is made by OpenAI, an AI research company founded in 2015. OpenAI also makes the underlying model family (GPT — Generative Pre-trained Transformer) that powers ChatGPT and their API. The company has released multiple generations of the GPT model, with GPT-4 being the most capable as of this writing.

What Can ChatGPT Do?

Answer questions — From factual questions ("What's the capital of Brazil?") to complex explanatory questions ("How do HTTP keep-alive connections work?"), ChatGPT can respond meaningfully to a very wide range of topics.

Write content — Emails, blog posts, marketing copy, reports, social media posts, cover letters. ChatGPT can draft content quickly, though it works best as a starting point for human editing rather than a final product.

Write and explain code — ChatGPT handles most major programming languages and can write functions, explain what existing code does, help debug errors, and suggest improvements.

Summarise documents — Paste a long document, report, or article and ask for a summary. ChatGPT reads and condenses effectively.

Brainstorm and ideate — Generate lists of ideas, angles, product names, or options for a decision. It's faster than a blank page.

Translate — Between most major languages, often with reasonable quality.

Explain complex topics — Ask it to explain machine learning, legal concepts, financial instruments, or scientific ideas. You can ask follow-up questions to go deeper.

How ChatGPT Works

ChatGPT is built on a large language model trained on a vast corpus of text data — books, websites, code, and other written material. The model learned to predict what text comes next given a sequence of input.

Through additional training using human feedback (reinforcement learning from human feedback, or RLHF), the model was shaped to respond helpfully, follow instructions, and avoid harmful outputs.

When you send a message, the model processes your entire conversation history and generates a response token by token — producing text that's contextually appropriate, coherent, and (usually) accurate.

For a deeper explanation of how this works technically, see how does AI work.

ChatGPT vs Claude

ChatGPT and Claude are the two most commonly compared AI assistants. Both are large language models, both can handle a very wide range of tasks, and both have free and paid tiers.

The differences come down to specific strengths and company philosophies. Claude (made by Anthropic) tends to be preferred for long-document analysis and coding tasks by many developers. ChatGPT's wide adoption means more tutorials, integrations, and third-party plugins exist for it.

See Claude AI vs ChatGPT for a full comparison.

What ChatGPT Gets Wrong

ChatGPT is impressive but not infallible. Important limitations:

Hallucinations — ChatGPT can produce confident-sounding but incorrect information. It may cite papers that don't exist, give wrong dates, or misstate facts. Always verify important claims against primary sources.

Knowledge cutoff — The model's training data has a cutoff date. It doesn't know about events or developments after that date unless it has web access enabled.

No real-time information — The base model doesn't have access to the live internet. ChatGPT Plus has a web browsing feature, but the base version is working from training data only.

Inconsistency — Ask the same question twice and you may get different answers. The model generates probabilistically, not deterministically.

Free vs Paid

ChatGPT is available in a free tier (with usage limits) and a paid tier (ChatGPT Plus) that provides access to the more capable GPT-4 model, faster responses, and additional features including plugins and image generation via DALL-E.

For developers, OpenAI also offers API access — see the OpenAI API tutorial for how to build ChatGPT-powered applications.

Building Applications With ChatGPT

Developers can integrate ChatGPT's capabilities into their own applications via the OpenAI API. This powers everything from customer service chatbots to code review tools to intelligent document processors.

When you build an application on top of ChatGPT's API, your application becomes dependent on external AI infrastructure — meaning uptime and availability matter more than ever. If the AI API has issues, or if your own server has problems, users lose access to the features they depend on.

Domain Monitor monitors your AI-powered applications and endpoints every minute from multiple global locations, alerting you the moment something goes down. Create a free account and set up monitoring for your application before launch — it takes minutes and means you find out about downtime before your users do.

The Practical Takeaway

ChatGPT is a capable, general-purpose AI assistant that handles a wide range of tasks well. It's genuinely useful for drafting, coding, summarising, explaining, and brainstorming.

Use it with an understanding of its limits: verify important facts, treat output as a draft rather than a finished product, and know that it doesn't have real-time information. Within those parameters, it's one of the most useful productivity tools available.

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