"\n" is a so-called “escape sequence.” An escape sequence is a string character written as a backslash followed by a code, which can be one or multiple characters. Python interprets escape sequences in a string as a special character.

Besides the newline character "\n", in Chapter 4¹ I also introduced the special characters "\'" and "\"", which can be used to place a single respectively double quote in a string, regardless of what characters surround the string. I also mentioned that you can use "\\" to insert a “real” backslash in a string.

Besides these, there are a few more escape sequences which lead to a special character. Most of these are archaic and you do not need to worry about them. The two I want to mention are "\t" which represents a single tabulation, and "\xnn" whereby nn stands for two hexadecimal digits, which represents the character with hexadecimal number nn. For example, "\x20" is the character expressed by the hexadecimal number 20, which is the same as the decimal number 32, which is the space (this will be explained later in this chapter).

In case you never learned about hexadecimal counting: hexadecimals use a numbering scheme that uses 16 different digits, namely 0 to 9, and A to F. A direct translation from hexadecimals to decimals turns A into 10, B into 11, etcetera. In decimal counting, the value of a multi-digit number is found by multiplying the digits by increasing powers of 10, from right to left, e.g. 1426 is

\[\begin{align} 1426 &= 1 \times 10^3 + 4 \times 10^2 + 2 \times 10^1 + 6 \times 10^0 \\ &= 1 \times 1000 + 4 \times 100 + 2 \times 10 + 6 \times 1 \end{align}\]

For hexadecimal numbers you do the same thing, but multiply by powers of 16, e.g., the hexadecimal number 4AF2 is

\[\begin{align} \text{4AF2} &= 4 \times 16^3 + 10 \times 16^2 + 15 \times 16^1 + 2 \times 16^0 \\ &= 4 \times 4096 + 10 \times 256 + 15 \times 16 + 2 \times 1 \end{align}\]

Programmers tend to like hexadecimal numbers, as computers work with bytes as the smallest unit of memory storage, and a byte can store 256 different values, i.e., any byte value can be expressed by a hexadecimal number of two digits.

Why it is useful to know about hexadecimal counting and hexadecimal representation of characters follows later in the book.