There are three quoting mechanisms: the escape character, single quotes, and double quotes. A non-quoted backslash (\) is the escape character. It preserves the literal value of the next character that follows, with the exception of <newline>.

If a \<newline> pair appears, and the backslash is not itself quoted, the \<newline> is treated as a line continuation (that is, it is removed from the input stream and effectively ignored).

Enclosing characters in single quotes preserves the literal value of
each character within the quotes. A single quote may not occur Between single quotes, even when preceded by a backslash.

Enclosing characters in double quotes preserves the literal value of all characters within the quotes, with the exception of $, ‘, and \. The characters $ and ‘ retain their special meaning within double quotes. The backslash retains its special meaning only when followed
by one of the following characters: $, ‘, ", \, or <newline>. A double quote may be quoted within double quotes by preceding it with a backslash. When command history is being used, the double quote may not be used to quote the history expansion character.