This is actually several separate C++11/C++14/C++17 libraries: * "date.h" is a header-only library which builds upon . It adds some new duration types, and new time_point types. It also adds "field" types such as year_month_day which is a struct {year, month, day}. And it provides convenient means to convert between the "field" types and the time_point types. * "tz.h" / "tz.cpp" are a timezone library built on top of the "date.h" library. This timezone library is a complete parser of the IANA timezone database. It provides for an easy way to access all of the data in this database, using the types from "date.h" and . The IANA database also includes data on leap seconds, and this library provides utilities to compute with that information as well. * "iso_week.h" is a header-only library built on top of the "date.h" library which implements the ISO week date calendar. * "julian.h" is a header-only library built on top of the "date.h" library which implements a proleptic Julian calendar which is fully interoperable with everything above. * "islamic.h" is a header-only library built on top of the "date.h" library which implements a proleptic Islamic calendar which is fully interoperable with everything above. WWW: https://github.com/HowardHinnant/date