Is Dart a single-threaded or multi-threaded language?

Dart is a single-threaded language but supports isolates for parallel computations. The main thread executes all code by default, including building the user interface. Isolates are independent workspaces with their own memory and event loop, which communicate by passing messages.

This allows resource-intensive operations, such as network requests or data processing, to run in the background without blocking the main thread, ensuring a smooth user interface.