How to: Date and Time Processing
* [biz](https://github.com/zendesk/biz) - Time calculations using business hours.
* [business_time](https://github.com/bokmann/business_time) - Support for doing time math in business hours and days.
* [ByStar](https://github.com/radar/by_star) - Find ActiveRecord objects by year, month, fortnight, week and more!
* [Chronic](https://github.com/mojombo/chronic) - A natural language date/time parser written in pure Ruby.
* [date_range_formatter](https://github.com/darkleaf/date_range_formatter) - The simple tool to make work with date ranges in Ruby more enjoyable.
* [groupdate](https://github.com/ankane/groupdate) - The simplest way to group temporal data in ActiveRecord, arrays and hashes.
* [holidays](https://github.com/holidays/holidays) - A collection of Ruby methods to deal with statutory and other holidays.
* [ice_cube](https://github.com/seejohnrun/ice_cube) - A date recurrence library which allows easy creation of recurrence rules and fast querying.
* [Jekyll-Timeago](https://github.com/markets/jekyll-timeago) - A Ruby library to compute distance of dates in words, with localization support, alternative styles, CLI and Jekyll support.
* [local_time](https://github.com/basecamp/local_time) - Rails Engine for cache-friendly, client-side local time.
* [montrose](https://github.com/rossta/montrose) - a simple library for expressing, serializing, and enumerating recurring events in Ruby.
* [stamp](https://github.com/jeremyw/stamp) - Format dates and times based on human-friendly examples, not arcane strftime directives.
* [time_diff](https://github.com/abhidsm/time_diff) - Calculates the difference between two time.
* [timezone](https://github.com/panthomakos/timezone) - Accurate current and historical timezones and transformations, with support for Geonames and Google latitude - longitude timezone lookups.
* [TZinfo](https://github.com/tzinfo/tzinfo) - Provides daylight savings aware transformations between times in different timezones.
* [validates_timeliness](https://github.com/adzap/validates_timeliness) - Date and time validation plugin for ActiveModel and Rails.
* [working_hours](https://github.com/intrepidd/working_hours) - A modern ruby gem allowing to do time calculation with working hours.
* [yymmdd](https://github.com/sshaw/yymmdd) - Tiny DSL for idiomatic date parsing and formatting.