The Calendar App is used for patients to make appointments for the medical service provider. It has three parts: 1. Patients' registration to the app with their email addresses. 2. The login with password. Forgot password form is provided. 3. Appointment scheduling: Can make appointment, reschedule appointment or cancel appointment. This app not only reduces the workload for the receptionists in medical offices, but also make it easier for patients to make and check appointments for their visits to the doctor office.