Scheduler is a powerful feature in Zoho Creator that allows the application owner to create timed actions without any user input. These timed actions can be executed periodically based on the date and time values present in your form or on fixed date and time.
Zoho Creator supports three types of schedules. Form, Report & Custom. For birthdate reminders you need to use Form. Form schedules are events that are scheduled based on a date/time field in your form. (i.e) you will be able to specify a field in the form, whose value will be taken as the scheduling due date (or as start date and end date) in case of schedules with repeats like 'monthly' or 'yearly'.