# What are Realms?
A realm object abstracts the notion of a distinct global environment, with its own global object, copy of the standard library, and "intrinsics" (standard objects that are not bound to global variables, like the initial value of Object.prototype). page
# Intuitions - sandbox - iframe without DOM - principled version of Node's 'vm' module - sync Worker
# Use cases - security isolation (with synchronous but coarse-grained communication channel) - plugins (e.g., spreadsheet functions) - in-browser code editors - server-side rendering - testing/mocking (e.g., jsdom) - in-browser transpilation