What is XML (Extensible Markup Language)?

XML (eXtensible Markup Language) is a simple markup language similar to HTML language used in web design, and it facilitates the representation, storage, and transmission of various information by computer applications, computers, and digital media where e-commerce services are provided.

What is XML (Extensible Markup Language)?

What is XML, and What Does it Do?

XML is not a programming language designed to perform specific tasks but provides a framework for meeting different needs faster. Some languages that support the framework structure are; it is XHTML, XSLT, and SOAP.

XML consists of a set of rules representing information that can be easily understood and processed by a computer and aims at simplicity and usability on the Internet. Since its structure is based on text characters, it supports almost all languages.

The first reason for the development of XML structure was to overcome the difficulties of large-scale electronic information publishing, but in time it began to be widely used for information exchange on the web in line with the increasing needs of users.


In 1996, XML was developed at the request of the World Wide Web Consortium to create a standard that would allow integrating the expression possibilities of HTML and GML (Generalized Markup Language). It started with the intention of creating a standard in a markup language. The GML language was developed by IBM (International Business Machine) in the 1960s and 1970s.

XML is designed to overcome the difficulties of HTML language, remove the limitations in sharing information with other devices, and provide easier usability for presenting various information on the screen depending on the browser used.

In the GML structure, it is allowed to save larger volumes of information along with classifying and writing any document.

ISO started to show interest in this new language as it is responsible for global standards and then presented SGML (Standard Generalized Markup Language) in 1986.

The main purpose of the XML language was to distinguish the content and structure of documents prepared for presentation on paper or on screen, but this purpose later paved the way for the creation of documents whose structure and informational content could be easily exchanged and processed on other computer systems.

XML offers management for online marketing systems or a service provider and is also used to retrieve, modify, and encode the created content through metadata. Therefore, this language is used successfully in academic, business, or institutional fields due to its popularity. Different working areas have been developed with computer applications suitable and designed to work with this language.

The DITA (Darwin Information Typing Architecture) program was developed for the professional creation of business documents and coding and reuse of technical documents.

Later, new versions of computer programs were developed with the acquisition of DB XML, Astoria, and Advent Publishing platforms by Sleepycat Software by Arbortext. These developments paved the way for the widespread use of XML in the information world.

Since 2005, the integration of computer applications to exchange data via web services has become popular. Thus, synchronization of data processing to documents using XML was started with the developed utilities.


An XML document consists of tags arranged in hierarchical ways, with each tag representing an entity. The scope of a label used is up to the supplementary label that covers it.


XML specifications use a parser that rejects documents that do not meet the basic rules, and this language has been further strengthened to avoid incorrect specification of structures found in most HTML documents.

Therefore, there are three types of XML documents: valid, invalid, and well-structured. Invalid documents do not follow syntax rules.

If a developer has defined the rules for a document using a DTD (Document Type Definition) or Schema (Schema) and the document does not follow these rules, this document is invalid.

Valid documents must follow both syntax rules and rules defined by their DTD or Schema structures. In well-formed documents, it follows the syntax rules but is not compatible with the DTD or Schema structure.

DTD defines the sequences and classifications and other basic details of elements that can appear in an XML document. DTDs are part of the original XML specification and are similar to the SGML DTD structure.

XML Schema defines all document structures that can be defined with DTD and has much more complex data types and rules than can be done with DTD.

W3C developed the Schema specification after its original specification. DTD defines the structure of its document, the type of each data it contains, and these values are determined by attributes.


With XML, users can create their own tags and assign attributes to tags. Thanks to this feature, the structure, and layout in a document are completely separate.

User-created documents are stored in text format and the documents have a structure that can be understood by both computers and humans.

Each document contains relevant metadata and this metadata is more easily recognized by search engines on the web. In addition, data can be converted or exported to broadcast formats.

Because XML does not have a license type, it is considered an open standard and allows internationalization. Thus, it is compatible and works with any character set, including the UNICODE character set UTF-8.

Documents can be created easily because it has specific creation rules. It allows the information in the created documents to be shared between web pages, databases, or other platforms.


Content management systems manage the publication, storage, and distribution of a website’s publications in digital format.

For example, information such as stock status and lead time of products published on a commercial website can be managed through a specific software platform. Or, with the use of an XML formatted site map on websites that contain articles on solving many problems, the availability of relevant content by search engines can be provided.

By handling such processes, various integrated applications are provided for the maintenance and management of a website. Thus, the content is easily updated without having to know the physical locations of the web pages created with HTML coding on the server.

Thanks to the transmission of XML documents over the Internet, it offers easy processing and flexibility for integration into databases or operations that can work as part of a website, so it contributes to the development of any integration systems.

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