The date and time functions provide the ability to read the system time in various formats and to manipulate date information.
If you're unfamiliar with date programming, it may be useful to know the following terms. The UNIX epoch is 00:00.00, January 1, 1970, Coordinated Universal Time (UTC). A UNIX timestamp (often just called a timestamp) is the number of seconds since the UNIX epoch. In most current applications, this number is stored as a 32-bit integer, meaning that it will be valid until early 2038 as is. Many people expect the world to move on to 64-bit systems by then, however.
These functions are available by default when PHP is built; you don't have to give a special argument to the configure script to enable them.
PHP Functions Essential Reference. Copyright © 2002 by New Riders Publishing (Authors: Zak Greant, Graeme Merrall, Torben Wilson, Brett Michlitsch). This material may be distributed only subject to the terms and conditions set forth in the Open Publication License, v1.0 or later (the latest version is presently available at http://www.opencontent.org/openpub/). The authors of this book have elected not to choose any options under the OPL. This online book was obtained from http://www.fooassociates.com/phpfer/ and is designed to provide information about the PHP programming language, focusing on PHP version 4.0.4 for the most part. The information is provided on an as-is basis, and no warranty or fitness is implied. All persons and entities shall have neither liability nor responsibility to any person or entity with respect to any loss or damage arising from the information contained in this book.