What is the Extensible Markup Language?

Extensible Markup Language (XML) is a format for textual data that facilitates readability in documents for both machine and human readers. Through the various rules that XML sets, documents can be consistently encoded in a fashion that is clearly defined, according to W3Schools. To accommodate multiple forms of human language, XML features Unicode support.

Simplifying the Process

One of XML’s primary functions is to keep data management simple. The format itself is necessarily swift and versatile in order to meet the many different demands of distinct web data forms that it serves. In order to properly process XML data, a specially customized API can be employed

Originally, XML was developed in order to tackle large loads of electronically published material. In the current day, XML’s functionality has extended to countless different forms of web data that depend on it for proper readability.

Far from its origins as a niche electronic publishing assistance tool, XML now serves as a crucial component for many different document formats such as SOAP and RSS. Programs such as Open Office and iWork have adopted XML as the standard text format to be used.

In addition to being used in many different data interchange processes, XML is also used for the definition of certain types of media. When the format is used in order to define media types such as “text/xml”, the only implication is that the data itself is built upon a foundation of XML; the specific linguistic elements of the content found within, however, are not indicated.

Specific Terminology

The XML format contains a high number of specific constructs that each serve a distinct purpose. Certain constructs within XML are more commonplace than others, the most common of all being the simple “character.”┬áStrands of characters are what make up the composition of all XML documents, and virtually all different legal characters found within the Unicode can be included.

XML characters can be divided into two specific subsets: content characters and markup characters. The differentiation between content and markup is determined by special syntactic conditions of the string. Though the conditions are not absolute, they represent the most common standard for string classification.

Strings that begin with ampersands or end with semicolons, and strings that begin with right-facing chevrons or end with left-facing chevrons, are generally classified as markup. Any strings that do not have the chevron, semicolon, or ampersand conditions that would indicate a markup character are considered content characters.


There have been a number of advisory guidelines established in order to regulate the proper use of XML by developers. Some of the documents that specify XML guidelines include RFC 3470 and RFC 7303. The XML regulation documents indicate guidelines such as the format’s languages necessarily being ended with +xml.

Related Resource: Application Programming Interface


The XML language serves a crucial role in both data structure representation and everyday documentation. It could be argued that the implementation of Extensible Markup Language laid the foundation for modern data interchange as we know it.