Claude

Claude is a family of large language models (LLMs) developed by Anthropic, an American artificial intelligence company based in San Francisco. Named after Claude Shannon, the mathematician widely regarded as the father of information theory, Claude serves as the foundation for Anthropic's conversational AI assistant of the same name. The model family is designed for a broad range of natural language tasks, including text generation, summarization, analysis, coding, and reasoning, and is positioned within the industry as a safety-oriented alternative to other frontier models such as OpenAI's GPT series and Google's Gemini. Claude is available to end users through the claude.ai web and mobile applications and to developers through an application programming interface (API) as well as major cloud platforms.

Background

Anthropic was founded in 2021 by Dario Amodei and Daniela Amodei, together with a group of researchers who had previously worked at OpenAI, including Tom Brown, Chris Olah, Jared Kaplan, Sam McCandlish, and Jack Clark. The company was established with an explicit focus on AI safety research, and its stated mission is to ensure that transformative artificial intelligence systems benefit humanity. This orientation has shaped the design philosophy of Claude, with Anthropic placing particular emphasis on interpretability, alignment techniques, and controlled deployment.

The Claude models are built on the transformer architecture, the dominant paradigm for large language models since its introduction in 2017. Like comparable systems, Claude is pre-trained on large corpora of text and code and then refined using alignment techniques to make its outputs more helpful, harmless, and honest.

History and Development

Early Models (2023)

Anthropic publicly introduced Claude in March 2023, offering two initial variants: Claude, the flagship model, and Claude Instant, a lighter and faster version intended for lower-latency applications. At launch, Anthropic announced partnerships with companies including Slack, Notion, Quora (for its Poe platform), and DuckDuckGo, which integrated Claude into their products.

In July 2023, Anthropic released Claude 2, which featured an expanded context window of 100,000 tokens—allowing the model to process documents equivalent to hundreds of pages of text—along with improved coding, mathematical, and reasoning performance. The public-facing chatbot at claude.ai was launched at the same time, making Claude directly accessible to general users for the first time. In November 2023, the Claude 2.1 update increased the context window to 200,000 tokens and reduced the model's tendency to produce false statements, a phenomenon known as hallucination.

The Claude 3 Series (2024)

In March 2024, Anthropic released the Claude 3 family, organized into three performance tiers: Haiku (fastest and most compact), Sonnet (balanced), and Opus (most capable). The models introduced multimodal capability, enabling them to analyze images, charts, and documents in addition to text. Claude 3 Opus achieved top results on several industry benchmarks at the time of its release and was widely regarded as one of the most capable models available.

In June 2024, Claude 3.5 Sonnet was released, offering improved performance at higher speed and lower cost than Claude 3 Opus. This release also introduced Artifacts, a feature that allows users to view, edit, and build upon generated content such as code, documents, and diagrams in a dedicated workspace alongside the conversation. An upgraded version of Claude 3.5 Sonnet followed in October 2024, accompanied by a "computer use" capability in public beta, which enabled the model to interact with graphical user interfaces—moving cursors, clicking buttons, and typing text—in a manner analogous to a human operator.

Later Releases (2025)

In February 2025, Anthropic released Claude 3.7 Sonnet, described as a hybrid reasoning model capable of either giving near-instant responses or engaging in visible "extended thinking" for more complex problems. In May 2025, at its first developer conference, the company announced Claude Opus 4 and Claude Sonnet 4, which placed particular emphasis on coding ability, long-horizon task execution, and agentic workflows, in which the model plans and executes multi-step tasks with limited supervision. Alongside these models, Anthropic promoted Claude Code, a command-line tool that allows Claude to operate directly within software development environments.

Subsequent releases in 2025 included updated versions such as Claude Opus 4.1, Claude Sonnet 4.5, and Claude Haiku 4.5, which continued improvements in reasoning, programming, and agentic task performance. During this period, Anthropic's commercial valuation rose into the tens of billions of dollars, supported by major investments from technology companies including Amazon and Google.

Technical Characteristics

Claude models share several defining technical characteristics:

• Architecture and scale: The models are based on the transformer architecture and are trained on large datasets of text and code, though Anthropic does not publicly disclose detailed parameter counts or training data composition.
• Context window: Claude was notable for offering exceptionally long context windows early in its development, growing from 9,000 tokens in the first version to 100,000 and later 200,000 tokens, enabling the processing of lengthy documents, codebases, and conversations.
• Multimodality: Beginning with the Claude 3 series, models can accept image inputs alongside text, supporting document analysis, chart interpretation, and visual question answering.
• Tool use and agentic capabilities: The models support function calling, retrieval, and integration with external systems. In November 2024, Anthropic introduced the Model Context Protocol (MCP), an open standard intended to simplify connections between AI models and external data sources and tools, which was adopted by a number of other technology companies.
• Extended reasoning: Later models incorporate configurable reasoning modes in which the system can spend additional computation on problems requiring multi-step deliberation.

Constitutional AI and Safety Approach

A distinguishing feature of Claude's development is Constitutional AI, an alignment methodology described by Anthropic researchers in 2022. Rather than relying solely on human feedback to shape model behavior, Constitutional AI uses an explicit set of written principles—drawn in part from documents such as the Universal Declaration of Human Rights and established research on AI ethics—to guide an AI model in critiquing and revising its own outputs. This technique, a form of reinforcement learning from AI feedback (RLAIF), is intended to make the alignment process more scalable, transparent, and consistent, since the principles governing the model's behavior can be publicly stated and modified.

Anthropic has positioned honesty, harmlessness, and helpfulness as the core objectives of Claude's training. The company publishes usage policies, conducts extensive pre-deployment testing, and has contributed research on topics such as model interpretability, potential misuse of AI systems, and the behavioral characterization of large models, including studies of emergent "persona" vectors and situational awareness in language models.

Products and Availability

Claude is offered through several channels. The consumer-facing assistant at claude.ai provides free access to standard models and paid subscription tiers (Pro, Team, and Enterprise) with higher usage limits and access to the most capable models. Native mobile applications for iOS and Android were introduced in 2024. For developers, Anthropic offers a direct API, and the models are also hosted on Amazon Bedrock and Google Cloud Vertex AI, making Claude one of the few frontier model families available across multiple major cloud providers. Features available to users include Artifacts, Projects (shared workspaces with persistent context), file uploads and analysis, web search, and computer use.

Impact and Significance

Claude has played a significant role in the development and commercialization of generative artificial intelligence. Its early adoption of very long context windows, its multimodal capabilities, and its agentic features influenced the broader industry, while its performance on coding benchmarks made it a widely used tool among software developers. The Constitutional AI framework has been influential in alignment research as a prominent example of scalable oversight, and the Model Context Protocol has become a widely referenced standard for connecting AI systems to external tools and data.

Anthropic's rapid commercial growth—reflected in substantial funding rounds, enterprise adoption, and annualized revenue estimates in the billions of dollars by the mid-2020s—has made Claude one of the leading commercial LLM platforms alongside those of OpenAI and Google. At the same time, the system has been the subject of ongoing public debate concerning the societal effects of advanced AI, including labor market impacts, misinformation risks, and questions of long-term safety, areas in which Anthropic has both conducted research and advocated for regulatory frameworks.

As of the mid-2020s, Claude remains in active development, with new model versions and capabilities released at regular intervals, and it continues to serve as the central product around which Anthropic's research and business activities are organized.