Single- and Double-Quoted Strings Are the Same

Around Python strings, single and double quote characters are interchangeable. That is, string literals can be written enclosed in either two single or two double quotes—the two forms work the same and return the same type of object. For example, the following two strings are identical, once coded:

>>> 'shrubbery', "shrubbery"
('shrubbery', 'shrubbery')

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The reason for supporting both is that it allows you to embed a quote character of the other variety inside a string without escaping it with a backslash. You may embed a single quote character in a string enclosed in double quote characters, and vice versa:

>>> 'knight"s', "knight's"
('knight"s', "knight's")

Incidentally, Python automatically concatenates adjacent string literals in any expression, although it is almost as simple to add a + operator between them to invoke concatenation explicitly (as we’ll see in Chapter 12, wrapping this form in parentheses also allows it to span multiple lines):

>>> title = "Meaning " 'of' " Life"        # Implicit concatenation
>>> title
'Meaning of Life'

Notice that adding commas between these strings would result in a tuple, not a string. Also notice in all of these outputs that Python prefers to print strings in single quotes, unless they embed one. You can also embed quotes by escaping them with backslashes:

>>> 'knight\'s', "knight\"s"
("knight's", 'knight"s')

To understand why, you need to know how escapes work in general.