Convert HTML to string (with backslash concatenation).

HTML to string (backslash concatenation) means converting an HTML code into a string format using backslashes to concatenate (join) different parts of the HTML code. For example, if we have an HTML code with tags and attributes, we can convert it to a string format by adding backslashes at the end of each line and concatenating it with the next line using a backslash. This way, we can store or transmit the HTML code as a string data type.