Details

Day of Month
d    Numeric, with leading zeros    01–31
j    Numeric, without leading zeros    1–31
S    The English suffix for the day of the month    st, nd or th in the 1st, 2nd or 15th.

Weekday
l    Full name  (lowercase ‘L’)    Sunday – Saturday
D    Three letter name    Mon – Sun

Month
m    Numeric, with leading zeros    01–12
n    Numeric, without leading zeros    1–12
F    Textual full    January – December
M    Textual three letters    Jan – Dec

Year
Y    Numeric, 4 digits    Eg., 1999, 2003
y    Numeric, 2 digits    Eg., 99, 03

Time
a    Lowercase    am, pm
A    Uppercase    AM, PM
g    Hour, 12-hour, without leading zeros    1–12
h    Hour, 12-hour, with leading zeros    01–12
G    Hour, 24-hour, without leading zeros    0-23
H    Hour, 24-hour, with leading zeros    00-23
i    Minutes, with leading zeros    00-59
s    Seconds, with leading zeros    00-59
T    Timezone abbreviation    Eg., EST, MDT …

Full Date/Time
c    ISO 8601    2004-02-12T15:19:21+00:00
r    RFC 2822    Thu, 21 Dec 2000 16:01:07 +0200
U    Unix timestamp (seconds since Unix Epoch)    1455880176