WHAT IT IS
Leading LLM families include Anthropic's Claude, OpenAI's GPT series, Google's Gemini, Meta's Llama, and Mistral's open models. Models are described by parameter count, context window length, and capability benchmarks (MMLU, HumanEval, GPQA). Open-weights models can be self-hosted; proprietary models are typically API-consumed with managed guardrails.
HOW IT WORKS
Production LLM applications add structure around the raw model: system prompts, retrieval-augmented generation (RAG) for grounding, tool/function calling, evaluation harnesses (golden datasets, LLM-as-judge), content safety, and cost/latency monitoring. A good LLM product is 90% the plumbing, 10% the model choice.
WHEN TO USE
Deploy an LLM when the workload is language-heavy, pattern-rich, and tolerates probabilistic output with human review. Avoid it for deterministic rules where traditional software is cheaper and safer.