A calendar app is a digital tool designed to help users organize their schedules and manage time effectively. It allows individuals to create, edit, and view events, appointments, and reminders. Most calendar apps sync across devices, ensuring that users can access their schedules from smartphones, tablets, or computers. Many calendar apps offer additional features, such as sharing events with others, setting recurring reminders, and integrating with other applications like email or task management tools. Popular examples include Google Calendar, Apple Calendar, and Microsoft Outlook Calendar, each providing unique functionalities to enhance productivity.