* **Module Datetime provides Date (`'<D>'`), Time (`'<T>'`) and Datetime (`'<DT>'`) classes.**

* **Time and Datetime can be 'aware' (`'<a>'`), meaning they have defined timezone, or 'naive' (`'<n>'`), meaning they don't.

$ pip3 install pytz

from datetime import date, time, datetime, timedelta

import pytz

<D> = date(year, month, day)

<T> = time(hour=0, minute=0, second=0, microsecond=0, tzinfo=None, fold=0)

<DT> = datetime(year, month, day, hour=0, minute=0, second=0, microsecond=0, tzinfo=None, fold=0)

<TD> = timedelta(days=0, seconds=0, microseconds=0, milliseconds=0, minutes=0, hours=0, weeks=0)

* **`'fold=1'` means second pass in case of time jumping back for one hour.**

* **Use `'<D/DT>.weekday()'` to get day of the week (Mon == 0).

<D> = date.today() # Current local date.

<DTn> = datetime.today() # Naive datetime from current local time.

<DTn> = datetime.utcnow() # Naive datetime from current UTC time.

<DTa> = datetime.now(<tz>) # Aware datetime from current <tz> time.

```python

<D/T/DT> = D/T/DT.fromisoformat(<str>) # From 'YYYY-MM-DD', 'HH:MM:SS.ffffff[+<offset>]' or both.

<DT> = DT.strptime(<str>, '<format>') # Datetime from string according to 'format'.

<D/DTn> = D/DT.fromordinal(<int>) # Date or datetime from days since Christ.

<D/DTn> = D/DT.fromtimestamp(<real>) # Date or datetime from seconds since Epoch in local time.

<DTn> = DT.utcfromtimestamp(<real>) # Naive datetime from seconds since Epoch in UTC time.

<DTa> = DT.fromtimestamp(<real>, <tz>) # Aware datetime from seconds since Epoch in <tz> time.

* **On Unix systems Epoch is `'1970-01-01 00:00 UTC'`, `'1970-01-01 01:00 CET'`, ...**

<str> = <D/T/DT>.isoformat() # 'YYYY-MM-DD', 'HH:MM:SS.ffffff[+<offset>]' or both.

<str> = <D/T/DT>.strftime('<format>') # Returns customized string representation.

<int> = <D/DT>.toordinal() # Returns days since Christ ignoring time and timezone.

<float> = <DT>.timestamp() # Returns seconds since Epoch in local time or <tz> if set.

>>> dt = datetime.strptime('2015-05-14 23:39:00', '%Y-%m-%d %H:%M:%S')

* **`'y'` - Year, 2 digits**

* **`'b'` - Month, abbreviated name**

* **`'B'` - Month, full name**

* **`'a'` - Weekday, abbreviated name**

* **`'A'` - Weekday, full name**

* **`'I'` - Hours, 2 digits, 12 hours**

* **`'p'` - AM/PM**

* **`'f'` - Microseconds, 6 digits**

* **`'z'` - Timezone offset, ± and 4 digits**

* **`'Z'` - Timezone name**

<tz> = pytz.timezone('<Continent>/<City>') # Use 'pytz.utc' for UTC.

<DTa> = <DT>.astimezone(<tz>) # Converts datetime to passed timezone.

<Ta/DTa> = <T/DT>.replace(tzinfo=<timezone>) # Changes timezone without conversion.

<timedelta> = <T/DT>.utcoffset() # Returns timezone's current offset from UTC.

<timedelta> = <T/DT>.dst() # Returns daylight saving time offset.