XML, or Extensible Markup Language, is a standard for structuring and storing data in a text format that is both human-readable and machine-readable. It was developed by the World Wide Web Consortium (W3C) in the late 1990s as a simplified subset of SGML (Standard Generalized Markup Language). Unlike HTML, which is designed to display information, XML is intended to carry and describe data through a system of custom tags defined by the user.

The central purpose of XML is to provide a flexible and consistent way to represent data across platforms and applications. XML separates data from its presentation, allowing for the exchange of information between different systems without concern for hardware or software differences. It is widely used for web services, document storage, and data interchange.

An XML document is built from a series of elements enclosed in tags. Every element has both an opening tag and a closing tag, and elements can be nested inside one another to form a hierarchical structure. Attributes can be added within tags to provide extra information. A typical XML file begins with a declaration such as:

<?xml version="1.0" encoding="UTF-8"?>
<book>
  <title>Understanding XML</title>
  <author>Care Code</author>
  <year>2025</year>
</book> 

• Self-descriptive: Tags are chosen by the user, making the meaning of data clear.

• Platform independent: XML can be read and processed on any operating system or device.

• Extensible: Users are not restricted to a fixed set of tags; they can create tags that fit their data needs.

• Unicode support: XML can store and represent almost any written human language.

XML is widely applied in many domains:

• Web services: Protocols such as SOAP and XML-RPC rely on XML for exchanging information between applications.

• Configuration files: Many software systems use XML files to define settings and preferences.

• Data interchange: XML makes it possible to transfer structured data between databases, applications, and organizations.

• Publishing: Digital publishing platforms and e-book formats often depend on XML.

• Scientific and medical records: XML schemas help standardize the exchange of sensitive data.

1. Advantages

• Simple, readable, and widely supported.

• Provides a universal format for structured data.

• Facilitates interoperability between different technologies.

2. Limitations

• Verbose compared to other formats such as JSON.

• Processing can be slower when documents become large.

• Requires careful schema design to avoid inconsistencies.