Claude: The Complete Guide to Anthropic's AI

What is Claude in 2026?

Claude is Anthropic's AI assistant, currently the leader in nuanced reasoning, careful writing, and agentic coding. The lineup is fast-moving — as of May 2026, the flagship is Claude Opus 4.7 (released April 16, 2026), with the upcoming Sonnet 4.8 expected to skip 4.7 and land in mid-2026.

Current Model Lineup (May 2026)

Claude Opus 4.7 — The most capable model. First Claude with high-resolution vision (2576px / 3.75MP, up from 1568px). 1M token context window, 128K max output. Strong at long-horizon reasoning and complex agentic workflows. Pricing: $5/M input, $25/M output (unchanged from 4.6, but uses ~1-1.35x more tokens due to new tokenizer).
Claude Sonnet 4.6 — Released Feb 17, 2026. The first Sonnet to beat the previous generation's Opus on coding benchmarks. The recommended default for most tasks — excellent quality at lower cost.
Claude Haiku 4.5 — The fastest model. Best for high-volume, latency-sensitive applications.
Sonnet 4.8 — Expected mid-2026 (4.7 was skipped per leaked changelog references).

Claude Code: Terminal CLI

Claude Code is Anthropic's official AI coding tool. The CLI version remains the most powerful option for developers who live in the terminal.

Installing the CLI

npm install -g @anthropic-ai/claude-code

Or via Homebrew on macOS: brew install --cask claude-code. Requires Node.js 18+ and an Anthropic account (Pro, Max, Team, or Enterprise plan).

First Run

cd /your/project
claude

Claude Code reads your repo, indexes it semantically, and presents an interactive prompt. Ask it questions, request changes, or give it tasks. It edits files, runs commands, and iterates until done.

Power Features

Sub-agents — Spawn specialized agents for parallel tasks (e.g., test runner + code reviewer simultaneously)
Plugins — Extensible via npm packages. Install MCP servers for database access, browser automation, etc.
Project memory — Drop a CLAUDE.md in your repo root. Claude reads it on every session.
Permissions — Granular control over what tools Claude can use without asking
Session resume — Long-running sessions persist via claude --resume

Claude Code: Desktop App (Redesigned April 2026)

On April 14, 2026, Anthropic released a complete redesign of the Claude Code desktop app for Mac and Windows. It now offers full parity with the CLI while adding visual workflow tools that the terminal can't.

Installation

Download from claude.com/download, install like any other desktop app, and sign in. The "Code" tab appears for Pro, Max, Team, and Enterprise users.

Key Desktop Features

Sidebar with multi-session management — see every active and recent session at a glance, filter by status/project/environment, group by project
Drag-and-drop workspace layout — arrange panels however you want
Integrated terminal — run tests, builds, scripts without leaving the app
In-app file editor — make spot edits without switching to your IDE
Rebuilt diff viewer — handles large changesets cleanly
Expanded preview pane — preview HTML, PDFs, and local app servers
Three view modes — Verbose (see every tool call), Normal (default), Summary (just results)
Plugin parity with CLI — your CLI plugins work identically in the desktop app
SSH support on Mac and Linux — point sessions at remote machines

When to Use Each

CLI — pure terminal workflows, scripting, headless servers, CI/CD pipelines
Desktop App — managing 3+ parallel sessions, visual diff review, mixed terminal + file editing in one place

Most professionals use both — desktop for active work, CLI for one-off automation.

Claude.ai (Web)

The classic chat interface at claude.ai. Best for non-coding tasks: writing, analysis, research, document review.

Plans (May 2026)

Free — Limited daily Sonnet usage
Pro ($20/mo) — Sonnet 4.6 + Opus 4.7 with higher limits, Projects, file uploads
Max ($100-200/mo) — 5-20x Pro limits, includes Claude Code access
Team / Enterprise — Org admin, SSO, audit logs, custom data residency

How to Get the Best Out of Claude

Be Specific About Output Format

Vague prompts get vague output. Compare:

❌ "Write about AI"
✅ "Write a 600-word blog post for non-technical readers explaining how transformers work, using a postal-service analogy. Tone: friendly. End with a 3-bullet summary."

Use Projects (claude.ai) or CLAUDE.md (Claude Code)

Both let you set persistent context. Upload your style guide, codebase docs, or domain knowledge once, and Claude uses them across every conversation.

Leverage the 1M Context

Drop entire books, codebases, or research papers in. Then ask specific questions: "Across these 50 customer interviews, what are the top 5 product complaints? Cite the interview and quote."

Iterate, Don't Restart

Claude maintains conversation context. Refining is faster than starting over: "Make the second paragraph more concrete", "Rewrite this in a more confident tone", "Add a counterargument".

Use Vision Strategically

Opus 4.7's high-res vision (2576px) reads UI screenshots, charts, and document scans far better than 4.6. Paste a Figma design and ask for the React code. Drop a research paper PDF and ask for a critique.

Claude vs GPT-5.5 vs Gemini 3.1 Pro

Claude wins on: nuanced writing, careful reasoning under uncertainty, code review and refactoring, willingness to say "I don't know" rather than hallucinate.

GPT-5.5 wins on: agentic computer use, multi-tool orchestration, raw benchmark scores, image generation (DALL-E).

Gemini 3.1 Pro wins on: Google Workspace integration, real-time web search grounding, native multimodal (video/audio).

Common Pitfalls

Token costs surprise you — Opus 4.7's new tokenizer uses up to 35% more tokens. Monitor usage on the API console.
Claude refuses something legitimate — Provide more context about your use case. Claude is more conservative than competitors but unblocks with explanation.
Long sessions degrade — Past ~100K tokens of conversation, start a new session and reload only the essential context.
You forgot to use Sonnet — Many people default to Opus. For 90% of tasks, Sonnet 4.6 is faster, cheaper, and good enough.