Customizing Date and Time in Rails

## Year
%Y  # with century 2007
%y  # without century 07
%C  # number (year divided by 100) 20

## Month
%B  # full month name January
%b  # abbreviated month name Jan
%h  # same as %b Jan
%m  # month as number (01-12)

## Week
%U  # week number of the year, Sunday as first day of week (00-53)
%W  # week number of the year, Monday as first day of week (00-53)

## Day
%A # full weekday name Wednesday
%a # abbreviated weekday name Wed
%d # day of the month (01-31)
%e # day of the month, single digits preceded by space ( 1-31)
%j # day of the year (001-366)
%w # weekday as a number, with 0 representing Sunday (0-6)
%u # weekday as a number, with 1 representing Monday (1-7)

## Time
%H # hour (24-hour clock) (00-23)
%k # hour (24-hour clock); single digits preceded by space ( 0-23)
%I # hour (12-hour clock) (01-12)
%l # hour (12-hour clock); single digits preceded by space ( 1-12)
%M # minute (00-59)
%S # seconds (00-59)
%p # either AM or PM AM
%Z # timezone name or abbreviation EDT
%z # timezone offset from UTC -0400

## Summaries
%D # date, same as %m/%d/%y 05/16/07
%v # date, same as %e-%b-%Y 16-May-2007
%F # date, same as %Y-%m-%d 2007-05-16
%R # time, 24 hour notation, same as %H:%M 18:06
%T # time, 24 hour notation, same as %H:%M:%S 18:06:15
%r # time, am/pm notation, same as %I:%M:%S %p 06:06:15 PM

## Formatting
%n # newline character
%t # tab character
%% # percent character

## Less common formats
%s # number of seconds since the Epoch, UTC
%c # national date and time representation
%+ # national date and time representation
%x # national date representation
%X # national time representation
%G # year with century, starting on first Monday where week has 4
or # more days.
%g # year without century, starting on first Monday where week has 4 or more days.
%V # week number of the year, starting on first Monday where week has 4 or more days.