AutoPostBackOnSelectionChanged:
AutoPostBackOnVisibleMonthChanged:
You can use the AutoPostBackOnSelectionChanged and AutoPostBackOnVisibleMonthChanged properties to indicate whether to postback to server when the user selects a date or navigates through months.

In this example the header has HTML image controls to navigate through years by using client-side API, while the footer has ASP.NET ImageButton server controls to navigate three months back and forward by using server-side API.