Date formatting is the process of displaying, handling or converting a calendar date to a specific format.
Wikipedia goes into good detail about various date formats in its Date format by country article:
Basic components of a calendar date for the most common calendar systems:
Y – Year
M – Month
D – Day
Order of the basic components:
B – Big-endian (year, month, day), e.g. 1996-04-22
L – Little-endian (day, month, year), e.g. 22.04.96 or 22/04/96
M – Middle-endian (month, day, year), e.g. 04/22/96
Specific formats for the basic components
yyyy – Four-digit year, e.g. 1996
yy – Two-digit year, e.g. 96
mm – Two-digit month, e.g. 04
m – one-digit month for months below 10, e.g. 4
mmm – three-letter abbreviation for month
mmmm – month spelled out in full
dd – two-digit day, e.g. 02
d – one-digit day for days below 10, e.g. 2
Separators of the components
"/" – Slash
"." – Dots or full stops
"-" – Hyphens or dashes
" " – Spaces
