<aside> 💡 Until Now everything you learned were necessary for creating a basic backend things below follow no such order, they are just some backend technologies used often or not used at all, these are for your knowledge and because they are used less they are some advanced stuff.

</aside>

XML

XML, which stands for Extensible Markup Language, was first introduced in 1996 and was designed for general-purpose use.

Developed by the World Wide Web Consortium (W3C), and used as a format to store and transfer data over the Web.

XML was designed to carry data, not to display data. In XML tags are not predefined. User defines his own meaningful tags.

XML is a generalized markup language. It offers a structured yet flexible syntax and a defined document schema.

• This makes it a good choice when working with complex configurations that require a structured format and finer control over schema validation to ensure configurations always have the correct format.

An XML document can be converted into another format, such as HTML and PDF, to make it more readable.

XML has been used to implement the following various operations, like:

• Configuration information
• Publishing
• Electronic Data Interchange (EDI)
• Voicemail system
• Remote Method Invocation (RMI)
• Object Serialization

XML's syntax can be verbose, redundant, and harder to read in comparison with other serialization languages.

XSL

XSL is a language for expressing style sheets. An XSL style sheet is, like with CSS, a file that describes how to display an XML document of a given type.

W3C developed XSL because an XML based stylesheet language was needed to transform XML documents.