Claude is the family of large language models (LLMs) developed by Anthropic, a US company founded in 2021 by former OpenAI staff and focused on AI safety.
The models come in several tiers, from the fastest and cheapest to the most capable (Haiku, Sonnet, Opus). They are known for writing code, analyzing long documents and using tools inside agents. Their training relies in particular on Constitutional AI, a method in which the model learns to follow a list of explicit principles.
Claude is available through the claude.ai app, Anthropic's API and the major clouds (AWS Bedrock, Google Cloud Vertex AI). Anthropic also offers Claude Code, a tool for handing development tasks to Claude directly in the terminal or the editor.
Anthropic also created MCP (Model Context Protocol), an open standard for connecting models to tools and data.
Why it matters when hiring
Knowing how to use Claude is not a rare skill. What matters for an AI Engineer or LLM Engineer: having built a production product on the API, with evaluation, cost control and error handling. In an interview, ask why one model was chosen over another: a real practitioner talks about comparative tests on their own use cases, not brand preference.