Python String join() method is a string method and returns a string in which the elements of the sequence have been joined by the str separator.

Python's join() method is a powerful tool for working with strings. It is a string method that is used to concatenate a list of strings with a specified delimiter. The join() method takes an iterable (such as a list or a tuple) of strings as its argument and returns a new string that is created by concatenating all the elements in the iterable separated by the delimiter.

The basic syntax of the join() method is as follows: 

string_name.join(iterable)

Here, string_name is the string that will be used as the delimiter to join the elements in the iterable. The iterable is the list of strings that will be joined.

For example, let's say we have a list of strings that we want to join together with a comma as the delimiter: 

fruits = ['apple', 'banana', 'orange']
result = ', '.join(fruits)
print(result)

Output: 

apple, banana, orange

In the above example, we first create a list of fruits, and then use the join() method to concatenate them with a comma delimiter. The resulting string is then printed to the console.

The join() method is a very useful tool for working with strings, and can be used in a wide variety of contexts, such as generating CSV files, building SQL queries, or creating HTML templates.