Calendar apps let you manage your events, activities, birthdays and general business and life matters.
As the name suggests calendar apps are calendar applications that usually sync with externally hosted cloud based servers to allow you to manage your daily activities.
Examples of Calendar Apps
Google Calendar
https://calendar.google.com
Apple Calendar
https://www.icloud.com/calendar
Microsoft Outlook Calendar
https://outlook.live.com
S planner
https://www.samsung.com
