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🧠 Understanding Large Language Models (LLMs)


This content originally appeared on DEV Community and was authored by Payal Baggad

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Large Language Models (LLMs) like GPT, Claude, and LLaMA are powering the latest wave of AI applications — from chatbots to code assistants. As developers, it’s important to know how these models work, what they can (and can’t) do, and how to use them effectively in your own projects.

🔹 What Are LLMs?

An LLM is an AI system trained on massive amounts of text data. It learns patterns in language and uses that knowledge to generate human-like responses.

Key terms to know:

  • Tokens → Words are broken into smaller units (tokens). The model predicts the next token.
  • Embeddings → Numeric representation of text that captures meaning.
  • Context Window → How much text the model can “remember” at once.

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🔹 Where Are LLMs Used?

  • Chatbots → Customer support, knowledge assistants.

  • Coding assistants → GitHub Copilot, Tabnine.

  • Content generation → Blogs, marketing, reports.

  • Data Q&A → Ask natural language questions on databases.

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🔹 Using LLMs in Code

Let’s try a quick example with Node.js + OpenAI API.

import OpenAI from "openai";

const client = new OpenAI({
  apiKey: process.env.OPENAI_API_KEY,
});

async function runLLM() {
  const response = await client.chat.completions.create({
    model: "llm-model", // replace with your chosen model
    messages: [
      { role: "user", content: "Explain React in 3 bullet points" }
    ],
  });

  console.log(response.choices[0].message.content);
}

runLLM();

🔹 Strengths and Limitations

✅ Great at: text generation, summarization, and brainstorming.

⚠ Weak at: real-time facts, math precision, hallucination (making things up).

As developers, we need to combine LLMs with external data sources or rules to make them reliable.

🎯 Conclusion

LLMs are changing the way we build applications, making natural language a new interface. They’re powerful but must be used carefully to avoid inaccuracies.

In the next post, we’ll explore Prompt Engineering, the art of asking better questions to get better answers from LLMs.


This content originally appeared on DEV Community and was authored by Payal Baggad