In technology, a header refers to supplementary data placed at the beginning of a block of information, often used in networking or file formats to provide metadata. Headers typically contain information like the source, destination, size, or type of the data that follows. In the context of web development, headers also refer to the pre-defined, introductory section of a webpage or the HTML elements enclosed in

tags for layout and presentation purposes.


The phonetic pronunciation of the keyword “Header” is ˈhɛdər (HEH-dər).

Key Takeaways

  1. Headers are used to provide introductory content or navigation links at the beginning of a webpage or section within a page.
  2. HTML headers are defined using the <header> element within a webpage’s code structure, making the content semantically correct and easily accessible by screen readers or other assistive technologies.
  3. Headers can contain various elements, such as headings (<h1> to <h6>), logos, images, and navigation links, which improve a webpage’s design and user experience.


Header is an essential term in technology because it refers to the supplemental information placed at the beginning of a data block, facilitating effective communication and interpretation across various protocols and applications.

Headers play a crucial role in organizing, structuring, and categorizing this information to ensure smooth data transmission, be it in network packets, file formats, or emails.

They often contain metadata, such as source and destination addresses, content type, and transmission protocols, which provide context and configuration parameters for recipients to interpret, process, and respond accordingly.

Due to their fundamental role in managing and streamlining the data exchange process, headers are indispensable components of modern digital communications.


Header, within the realm of technology, plays a crucial role in facilitating seamless communication and data exchange between different components and entities. One of its primary purposes is to convey vital metadata, enabling the proper interpretation and processing of the data it accompanies.

Headers can be found in various contexts, such as computer programming, web development, and network communication. In computer programming, headers serve as an introductory segment of a code file, encompassing necessary information and declarations that allow the program to function effectively.

For instance, they may include crucial library import statements, copyright agreements, or a brief description of the file’s purpose and functionality. In networking, headers are attached to a packet or datagram to transmit essential information such as the source and destination, ensuring the data’s accurate and efficient routing.

Similarly, in web development, HTTP headers are employed to exchange pertinent details between the server and client, including content type, character encoding, and cache instructions. Ultimately, headers provide a structured framework that streamlines complex technological interactions.

Examples of Header

I assume you’re referring to HTTP headers, a key aspect of communication in web technology. Here are three real-world examples of how headers are used:Content-Type Header:When you visit a website, your web browser sends an HTTP request to the server hosting the site. The server responds with an HTTP response containing the requested information. The “Content-Type” header is included to indicate the type of data being sent, such as HTML, plain text, images, or JSON. For example, a server may respond with “Content-Type: text/html” to signify that the response contains an HTML document.User-Agent Header:Browsers and other clients, such as mobile devices and robots, include the “User-Agent” header in their HTTP requests to servers. This header provides information about the client’s software, including name, version, operating system, and often other details. Websites may use this information to serve content optimized for a specific device or browser. For example, a client may include the header “User-Agent: Mozilla/

0 (Windows NT0; Win64; x64) AppleWebKit/36 (KHTML, like Gecko) Chrome/

82 Safari/36″ to identify itself as Google Chrome on WindowsCache-Control Header:The “Cache-Control” header is used to manage caching of web content. It can be included in both HTTP requests and responses to specify caching rules. For example, a server may use the “Cache-Control: public, max-age=3600” header to indicate that a resource can be cached by any client, and that it’s valid for 1 hour (3600 seconds). Similarly, a client can use the “Cache-Control: no-cache” header in its request to inform the server that it wants a fresh copy of the resource without using the cached version.


Question 1: What is Header?

Answer: A header is a section of a document or website that usually contains the logo, navigation, and other relevant information. It is placed at the top of the page and provides a consistent look and structure across the entire site.

Question 2: What are the different types of headers?

Answer: There are various types of headers, such as fixed headers, responsive headers, transparent headers, and full-width headers. Each type has its unique design and style, providing a different user experience depending on the website’s purpose and layout.

Question 3: How can I customize my header?

Answer: You can customize your header using HTML, CSS, and JavaScript. HTML is used for creating the structure, CSS for styling, and JavaScript for adding interactive elements. Some website builders also provide built-in tools for header customization, making it easy for non-technical users to modify their headers.

Question 4: Why are headers important in web design?

Answer: Headers are important in web design because they create a consistent look and feel across a website, improving usability and user experience. Headers also help increase brand recognition as they typically contain the logo and company information. Moreover, well-designed headers make it easy for users to navigate the site and find the information they need.

Question 5: Can a header include a search bar or social media icons?

Answer: Yes, a header can include a search bar or social media icons. Incorporating these elements into the header makes them easily accessible to users and enhances the website’s functionality. This can improve the overall user experience and encourage visitors to engage with the site.

Related Technology Terms

  • Meta tags
  • HTTP headers
  • Alt attribute
  • DOCTYPE declaration
  • Navigation bar

Sources for More Information


About The Authors

The DevX Technology Glossary is reviewed by technology experts and writers from our community. Terms and definitions continue to go under updates to stay relevant and up-to-date. These experts help us maintain the almost 10,000+ technology terms on DevX. Our reviewers have a strong technical background in software development, engineering, and startup businesses. They are experts with real-world experience working in the tech industry and academia.

See our full expert review panel.

These experts include:


About Our Editorial Process

At DevX, we’re dedicated to tech entrepreneurship. Our team closely follows industry shifts, new products, AI breakthroughs, technology trends, and funding announcements. Articles undergo thorough editing to ensure accuracy and clarity, reflecting DevX’s style and supporting entrepreneurs in the tech sphere.

See our full editorial policy.

More Technology Terms

Technology Glossary

Table of Contents