Chronograph watches can measure and display elapsed time. Usually three subcounters on the dial display the elapsed seconds, minutes and hours.
Regatta chronographs feature a countdown which indicates the last minutes before the beginning of a nautical race. It was designed to prevent skippers from crossing the start line too early.
A day date watch displays the days of the week (from monday to sunday) and the date (between 1 and 31).
The date is a small window on the dial which indicates the day of the month (between 1 and 31).