what are keyword arguments for functions?

Question

eg.key=len is for max() function

Answer 1

Its for defining the criteria to sort out max value from given data.
When you use len as a argument, you are declaring that max function should sort the data according to length of data

Answer 2

https://www.sololearn.com/Discuss/2045184/?ref=app

Answer 3

Have a look at this for more clear view
https://code.sololearn.com/ckEAWkJ8wahh/?ref=app

Answer 4

keyword arguments are usually used with dictionaries. As in:

args = {"key": <length>,
"name_list": <list_of_names>,
...}