You can surround characters with either single primes (′) or double primes (″) to create a string. But whichever symbol you use, you can’t use it again in the middle of the string because that will end the string early. However, you can escape any character with a backslash (
\) to solve this or use single primes inside double primes (and vice versa).
Escape sequences are useful for other things too, such as for newlines ...