GPT: the model family behind ChatGPT
GPT stands for Generative Pre-trained Transformer: a type of large language model that first learns from a large body of text, then generates new text. ChatGPT is a chat product built on GPT models.
See LLM hostingChecked 31 Oct 2026 · ZenoCloud Team
What does each letter mean?
Generative: it produces text. Pre-trained: it learns language from unlabelled text before it is adapted to a task. Transformer: the network design introduced in 2017.
OpenAI’s 2018 paper “Improving Language Understanding by Generative Pre-Training” set out the approach.
GPT or ChatGPT?
GPT is the model family. ChatGPT is the app that lets you talk to one.
Is every LLM a GPT?
No. Every GPT is an LLM, but other LLM families exist. Many are built on the same transformer design without using the GPT name.
What is the transformer?
Transformers use attention to relate tokens. GPT uses a decoder that attends to earlier tokens to predict the next one.
Questions people ask
Why is ChatGPT called GPT?
Because it runs on GPT models. “Chat” says it is a conversation interface; “GPT” names the model family underneath.
What is the difference between GPT and LLM?
LLM is the general category: a large model trained on text. GPT is one family inside it, first described by OpenAI in 2018.
Can I run a GPT model myself?
Some, yes. OpenAI has published open-weight gpt-oss models. OpenAI’s gpt-oss-120b is a mixture-of-experts model, 117B total and 5.1B active, shipped in MXFP4. The weights are about 65GB, so one 80GB GPU runs it, and so does a 96GB RTX PRO 6000.
Hosting a GPT-class model
Open models of this class need GPU memory that matches their weights; gpt-oss-120b fits one 80GB card. An H100 80GB starts at ₹1,80,000 a card a month, host included, before tax.
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