Why do Python's datetime.strftime('%w') and datetime.weekday() use different indexes for the days of the week?

Question

In Python, showing the day of the week as an integer using datetime.strftime() shows a different result than using datetime.weekday().

Answer 1

Maybe weekday is based on locale while strftime is not? Because I have different output:

In [14]: d.strftime("%A")
Out[14]: 'Sunday'

In [15]: d.strftime("%w")
Out[15]: '0'

In [16]: now.weekday()
Out[16]: 0