Application state refers to all the data an application needs to remember while running. State may include user input, UI selections, cached results, session data, or shared context across components. Managing state correctly ensures consistent behavior, predictable UI updates, and smooth user interactions.
Why it matters
Poorly managed state leads to bugs, UI inconsistencies, performance issues, and difficult debugging—especially in frontend frameworks. Understanding state is crucial for designing clean architecture and predictable application flows.
Examples
Tracking whether a sidebar is open or storing a logged-in user profile. Lessons like State Management Concepts provide deeper insights.