How to utilise date and time in PHP.

// 2021-07-01 15:44:00
$mysql_datetime = date("Y-m-d H:i:s");
 
// Thursday 1st July 2021
$human_datetime = date("l jS F Y");     
 
// Convert from 2021-03-01 to 01/03/2021
$change_format = date("d/m/Y", strtotime('2021-03-01'));

// OOP from 2024-02-22 to 22/02/2024
$datetime = DateTime::createFromFormat('Y-m-d', '2024-02-22');
$date_formatted = $datetime->format('d/m/Y');

// OOP current date in Y-m-d H:i:s format
$datetime= new DateTime();
$mysql_datetime = $datetime->format('Y-m-d H:i:s');

When using strtotime():

Date values separated by slash are assumed to be in American order: m/d/y
Date values separated by dash are assumed to be in European order: d-m-y

The following characters are recognized in the format parameter string:

Character	Description
Y	A full numeric representation of a year, 4 digits
m	Numeric representation of a month, with leading zeros
d	Day of the month, 2 digits with leading zeros
H	24-hour format of an hour with leading zeros
m	Numeric representation of a month, with leading zeros
i	Minutes with leading zeros
l	(lowercase 'L') A full textual representation of the day of the week
j	Day of the month without leading zeros
S	English ordinal suffix for the day of the month, 2 characters
F	A full textual representation of a month, such as January or March