TIdTimeUDP = class(TIdCustomTimeUDP);

TIdTime is a TIdUDPClient descendant descendant that implements a UDP_based Time Protocol client, as described in the Internet Standards document: 

RFC 868 - Time Protocol  

Time is a simple protocol for synchronizing time on a local network. This protocol provides a site-independent, machine readable date and time. The Time service sends back to the originating source the time in seconds since 00:00 (midnight) 1 January 1900 GMT, such that the time 1 is 12:00:01 am on 1 January 1900 GMT; this base will serve until the year 2036. 

One motivation for the protocol arises from the fact that not all systems have a date/time clock, and all are subject to occasional human or machine error. The use of time-servers makes it possible to quickly confirm or correct a system's idea of the time, by making a brief poll of several independent sites on the network. 

For a time protocol with higher accuracy over several networks, use TIdSNTP. To retrieve the current date and time in human-readable form, use TIdDayTime. 

The Time Protocol in its current form cannot handle most dates after the year 2036. This limitation is stated in RFC 868.