Escape sequences
For any text format that uses special characters we face the problem of how to express those characters when the data we have includes those special characters. This is general problem in computer science that leads to the idea of escape sequences.
This is a special sequence of characters which we use to represent these characters.
For instance in HTML < > and & are special characters which are expressed using the escape sequences we call HTML entities.
Forgetting to escape characters in the right context is a common source of bugs in programs.