An example of a date picker in use. When the user clicks on the entry field, a calendar pops up below.
An example of a date picker in use. When the user clicks on the entry field, a calendar pops up below.

A date picker, popup calendar, date and time picker, or time picker is a graphical user interface widget which allows the user to select a date from a calendar and/or time from a time range. The typical practice is to provide a text box field which, when clicked upon to enter a date, pops up a calendar next to or below the field, allowing the user to populate the field with an appropriate date, or provides a text box with an icon of a calendar such that when the icon is clicked on, the calendar (or time field) appears, or show calendar widget directly (inline).

The date picker provides several advantages, including:

In the case of a time picker, many similar functions are available, such as ensuring the user

An example of a programmable date picker is shown in the documentation for the jQuery UI JavaScript user interface library at: http://jqueryui.com/datepicker/