Linux uses the tz (sometimes known as the zoneinfo) database which is available from ftp://elsie.nci.nih.gov/pub.
The time zone files are in a binary format and so not human readable (the zdump command using the -v option renders it into such a form). These data files can reside anywhere on the system but are usually to be found in /usr/share/zoneinfo. The current timezone on a Linux system is to be found at /etc/localtime and is either a copy of the relevant zoneinfo file or is a symlink to it.