15.5Key Concepts

Browsing Context

A "browsing context" is a tab or iframe. Each has a unique ID.

Browser
├── Context "ctx-1" (Tab 1 - https://example.com)
│   ├── Context "ctx-2" (iframe - ad)
│   └── Context "ctx-3" (iframe - widget)
└── Context "ctx-4" (Tab 2 - https://docs.example.com)

User Context

User contexts provide isolation (like incognito profiles):

// Create isolated context
{"id": 1, "method": "browser.createUserContext", "params": {}}

// Create tab in isolated context
{"id": 2, "method": "browsingContext.create", "params": {
  "type": "tab",
  "userContext": "user-ctx-1"
}}

Event Subscriptions

Clients must explicitly subscribe to events they want:

// Subscribe to console logs and network events
{"id": 1, "method": "session.subscribe", "params": {
  "events": ["log.entryAdded", "network.beforeRequestSent"],
  "contexts": ["ctx-1"]  // Optional: only for specific tab
}}