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What is large language model? Plain-English meaning

A large language model is a type of artificial intelligence that has been trained on vast amounts of text to understand and generate human-like language.

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Definition

A large language model is a type of artificial intelligence that has been trained on vast amounts of text to understand and generate human-like language.

Also seen as: LLM, language model

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Last updated
September 7, 2026
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Technology & Internet
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Plain-English explanation

Large language models, often called LLMs, are computer programs that learn patterns from enormous collections of written text. They use those patterns to predict the next word in a sentence, which lets them answer questions, summarize documents, translate languages, and even write code. They are called 'large' because they have billions of parameters—the internal settings that help them learn—and because they are trained on huge datasets. These models don't truly understand meaning like a human does; they are very good at statistical pattern matching. However, that pattern matching is so advanced that the output often appears fluent and knowledgeable. Many modern AI chatbots and writing assistants are built on large language models.

Why it matters

Large language models are behind many tools you might use every day, such as chatbots, autocomplete features in email, and grammar checkers. Understanding what they are and how they work helps you know when to trust their outputs and when to be cautious. Because they can generate convincing text, it's important to remember that they can make mistakes or produce biased or incorrect information. Knowing their limitations helps you use them more effectively and critically.

Concrete example

When you use a customer support chat window on a website and the bot responds with a helpful answer, that bot might be powered by a large language model. Another example is using a tool that automatically writes a summary of a long news article—the tool uses an LLM to read the article and generate a concise summary. These are everyday uses of large language models.

Often confused with

People often confuse large language models with general artificial intelligence or with a search engine. A search engine finds existing web pages that match your query, while an LLM generates new text that might not exist anywhere. Also, an LLM is not a general AI that can reason about the world; it only processes and generates language. It doesn't have true understanding or common sense beyond what it learned from text.

Short definition: A large language model is a type of artificial intelligence that has been trained on vast amounts of text to understand and generate human-like language.

Plain-English explanation

Large language models, often called LLMs, are computer programs that learn patterns from enormous collections of written text. They use those patterns to predict the next word in a sentence, which lets them answer questions, summarize documents, translate languages, and even write code. They are called 'large' because they have billions of parameters—the internal settings that help them learn—and because they are trained on huge datasets. These models don't truly understand meaning like a human does; they are very good at statistical pattern matching. However, that pattern matching is so advanced that the output often appears fluent and knowledgeable. Many modern AI chatbots and writing assistants are built on large language models.

Why it matters

Large language models are behind many tools you might use every day, such as chatbots, autocomplete features in email, and grammar checkers. Understanding what they are and how they work helps you know when to trust their outputs and when to be cautious. Because they can generate convincing text, it's important to remember that they can make mistakes or produce biased or incorrect information. Knowing their limitations helps you use them more effectively and critically.

Concrete example

When you use a customer support chat window on a website and the bot responds with a helpful answer, that bot might be powered by a large language model. Another example is using a tool that automatically writes a summary of a long news article—the tool uses an LLM to read the article and generate a concise summary. These are everyday uses of large language models.

Common confusion

People often confuse large language models with general artificial intelligence or with a search engine. A search engine finds existing web pages that match your query, while an LLM generates new text that might not exist anywhere. Also, an LLM is not a general AI that can reason about the world; it only processes and generates language. It doesn't have true understanding or common sense beyond what it learned from text.

Related terms

artificial intelligence, neural network, natural language processing, chatbot

Practical tips

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More context

Large language models are built on the transformer architecture, which uses self-attention mechanisms to weigh the importance of different words in a sentence. They are typically pre-trained on a large corpus and then fine-tuned for specific tasks or to align with human preferences. The development of LLMs has accelerated rapidly, with models now capable of processing multiple modalities such as images and audio.

Sources and further reading

  1. SP 800-145, The NIST Definition of Cloud ComputingNational Institute of Standards and TechnologyNIST defines cloud computing, which runs on servers in large data centers, and its essential characteristics and service models.
  2. Function callingOpenAI API DocumentationFunction calling lets models access defined functionality and data through tools.
  3. HTML: HyperText Markup LanguageMDN Web DocsHTML structures web pages with elements, while CSS styles them and JavaScript adds behavior.
  4. JavaScriptMDN Web DocsJavaScript is a programming language that adds interactivity and behavior to HTML web pages.