PHP date() Function

It formats a local time/ date as follow:

d - The day of the month (from 01 to 31)
D - A textual representation of a day (three letters)
j - The day of the month without leading zeros (1 to 31)
l (lowercase 'L') - A full textual representation of a day
N - The ISO-8601 numeric representation of a day (1 for Monday through 7 for Sunday)
S - The English ordinal suffix for the day of the month (2 characters st, nd, rd or th. Works well with j)
w - A numeric representation of the day (0 for Sunday through 6 for Saturday)
z - The day of the year (from 0 through 365)
W - The ISO-8601 week number of year (weeks starting on Monday)
F - A full textual representation of a month (January through December)
m - A numeric representation of a month (from 01 to 12)
M - A short textual representation of a month (three letters)
n - A numeric representation of a month, without leading zeros (1 to 12)
t - The number of days in the given month
L - Whether it's a leap year (1 if it is a leap year, 0 otherwise)
o - The ISO-8601 year number
Y - A four digit representation of a year
y - A two digit representation of a year
a - Lowercase am or pm
A - Uppercase AM or PM
B - Swatch Internet time (000 to 999)
g - 12-hour format of an hour (1 to 12)
G - 24-hour format of an hour (0 to 23)
h - 12-hour format of an hour (01 to 12)
H - 24-hour format of an hour (00 to 23)
i - Minutes with leading zeros (00 to 59)
s - Seconds, with leading zeros (00 to 59)
e - The timezone identifier (Examples: UTC, Atlantic/Azores)
I (capital i) - Whether the date is in daylights savings time (1 if Daylight Savings Time, 0 otherwise)
O - Difference to Greenwich time (GMT) in hours (Example: +0100)
T - Timezone setting of the PHP machine (Examples: EST, MDT)
Z - Timezone offset in seconds. The offset west of UTC is negative, and the offset east of UTC is positive (-43200 to 43200)
c - The ISO-8601 date (e.g. 2004-02-12T15:19:21+00:00)
r - The RFC 2822 formatted date (e.g. Thu, 21 Dec 2000 16:01:07 +0200)
U - The seconds since the Unix Epoch (January 1 1970 00:00:00 GMT)

for example you can use this function to change a date format:
date("d M Y H:i:s" ,strtotime($the_date))

copied from here