PK Zip File Information
This format is designed for cross-platform data exchange and efficient data storage for a set of related files. ZIP_PK is a de facto industry standard, developed, maintained, and openly documented by PKWARE. The original version of the format was developed by Phil Katz (hence the "PK" in PKWARE). ZIP_PK combines data compression, file management, and data encryption within a portable archive format. A ZIP file is a package containing one or more files, usually compressed and sometimes encrypted. The basic structure consists of a sequence of chunks comprising a "local file header" followed by the file data (after compression and/or encryption) followed by a chunk known as the "central directory," which lists the files in the package along with key metadata to support their extraction, decryption, etc. Over the years the format has been extended by PKWARE to adapt to new expectations of users and to changing technology, for example, to allow improved methods for compression and encryption, to support larger file sizes, and to support UNICODE UTF-8 for filenames.
Reference Library of Congress

Initial Version 0.8  date 1-11-1989
Reference History
http://www.liquisearch.com/pkzip/history/version_history/pkzip