What is XML in web design?

Answer:-

XML means Extensible Markup Language.

XML is a general-purpose specification for creating custom markup languages.
It is classified as an extensible language, because it allows the user to define the mark-up elements.
XML's purpose is to aid information systems in sharing structured data, especially via the internet, to encode documents, and to serialize data in the last context, it compares with text-based serialization languages such as JSON, YAML and S-Expressions.

XML stands for eXtensible Markup Language.

XML is designed to transport and store data.

XML is important to know, and very easy to learn.