Keys are Rails TimeZone names, values are TZInfo identifiers.

The TimeZone class serves as a wrapper around TZInfo::Timezone instances. It allows us to do the following:

• Limit the set of zones provided by TZInfo to a meaningful subset of 146 zones.

• Retrieve and display zones with a friendlier name (e.g., “Eastern Time (US & Canada)” instead of “America/New_York”).

• Lazily load TZInfo::Timezone instances only when they're needed.

• Create ActiveSupport::TimeWithZone instances via TimeZone's local, parse, at and now methods.

If you set config.time_zone in the Rails Application, you can access this TimeZone object via Time.zone:

# application.rb:
class Application < Rails::Application
  config.time_zone = 'Eastern Time (US & Canada)'
end

Time.zone      # => #<TimeZone:0x514834...>
Time.zone.name # => "Eastern Time (US & Canada)"
Time.zone.now  # => Sun, 18 May 2008 14:30:44 EDT -04:00

The version of TZInfo bundled with Active Support only includes the definitions necessary to support the zones defined by the TimeZone class. If you need to use zones that aren't defined by TimeZone, you'll need to install the TZInfo gem (if a recent version of the gem is installed locally, this will be used instead of the bundled version.)