StrictMode is a tool for highlighting potential problems in an application.
Like Fragment, StrictMode does not render any visible UI. It activates additional checks and warnings for its descendants.

Note: Strict mode checks are run in development mode only; they do not impact the production build.

StrictMode currently helps with:

Identifying components with unsafe lifecycles
Warning about legacy string ref API usage
Warning about deprecated findDOMNode usage
Detecting unexpected side effects
Detecting legacy context API