What is an LLM (Large Language Model)?

What is an LLM (Large Language Model)?

An LLM is a type of artificial intelligence model designed to understand, generate, and manipulate human language. These models are trained on massive datasets of text and use deep learning techniques (especially transformers) to perform language tasks.

What is an LLM (Large Language Model)?

Key Features of LLMs

  • Built using transformer architectures (e.g., GPT, BERT)
  • Trained on internet-scale corpora (books, articles, websites)
  • Handle a wide range of tasks:
    • Text generation
    • Question answering
    • Summarization
    • Translation
    • Code generation
    • Sentiment analysis
  • Use billions to trillions of parameters

Key Characteristics of LLMs

  • Large Scale: They are called “large” because they are trained on massive amounts of text data (billions or even trillions of words from books, articles, websites, and code) and contain billions of adjustable parameters.
  • Deep Learning: LLMs are built using deep learning, a subset of machine learning, and rely on a special type of neural network architecture called a Transformer.
  • Prediction Machines: Fundamentally, an LLM works by being a sophisticated predictor. When you give it a prompt, it calculates the statistical probability of which word should come next, generating a coherent sequence of text word by word.

Popular LLMs (as of 2025)

ModelCreatorParametersKey Feature
GPT-4 / GPT-4oOpenAI~1T (est.)Multimodal (text, image, audio)
Claude 2/3AnthropicUnknownFocus on alignment, safety
Gemini 1.5Google DeepMindUnknownIntegrated with search & tools
LLaMA 3Meta8B, 70BOpen-source, efficient
MistralMistral AI7B, Mixtral 12x8BSparse mixture of experts
PaLM 2Google~540BUsed in Bard (now Gemini)
ERNIEBaiduProprietaryFocused on Chinese language
Command R+CohereProprietaryOptimized for RAG
Yi-34B01.AI34BMultilingual, open weights
WizardCoder / DeepSeekCoderOpen-source13B–34BTuned for coding

What LLMs Can Do

LLMs are versatile and can be adapted for a wide range of tasks:

  • Text Generation: Writing emails, articles, stories, poems, or any other form of creative or factual content.
  • Question Answering: Providing informed answers to user queries, often in a conversational style.
  • Summarization: Taking a long document and condensing it into a shorter, coherent summary.
  • Translation: Translating text between different human languages.
  • Code Generation: Writing or debugging software code based on a natural language description.
  • Chatbots & Conversational AI: Powering systems that can hold fluid, human-like conversations.

Applications of LLMs

  • Chatbots and virtual assistants
  • Writing and content generation
  • Programming help (e.g., GitHub Copilot)
  • Legal and medical document analysis
  • Education and tutoring
  • Translation and localization
  • Search engines (RAG = Retrieval-Augmented Generation)

🔷 Challenges and Concerns

  • Bias and fairness: May replicate harmful stereotypes
  • Hallucination: Confidently generating false or misleading information
  • Data privacy: Use of proprietary or sensitive training data
  • Compute and energy cost: Expensive to train and run
  • Misuse potential: Disinformation, deepfakes, phishing, etc.

Open-Source vs Proprietary LLMs

CategoryExamplesNotes
ProprietaryGPT-4, Claude, GeminiClosed weights, commercial APIs
Open-SourceLLaMA, Mistral, Falcon, BLOOMFree to use, can be fine-tuned locally

Future of LLMs

  • Multimodal models: Text + image + audio (e.g., GPT-4o, Gemini)
  • Smaller, more efficient LLMs: Edge computing, mobile deployment
  • Better alignment and control
  • Open-source dominance in research and startups