How Does a Browser Work?

Whether on a computer, a tablet or a smartphone: the way to access the Internet is usually through a web browser or Browser. We usually use Chrome, Mozilla Firefox or Safari to visit websites or make online purchases.

But what is a Web browser? We explain how this software works and provide a definition of the Web browser which is the real gateway to the Internet.

Meaning of web browser

A browser is a mainly free software that allows you to view Internet pages. With the help of a web browser, texts, images, videos, but also links and other functions of a website are displayed.

The term Browser is derived from the verb “to browse” and means to look at, leaf through or navigate. With the introduction of hypertext, references to navigation were added, called hyperlinks.

In the meantime, the range of functionality of browsers has expanded considerably: in addition to images and videos, interactive graphics, audio files, PDFs and other resources can now be integrated and provided with functions.

How does a Web browser work?

It is helpful to understand how this software works. When you enter a URL into your browser, it then requests the page from the target server. The server responds by returning the content in the form of HTML code, images and other resources.

Each resource is uniquely identified by a URI (Uniform Resource Identifier). Using certain specifications contained in the HTML and CSS files, the browser interprets all the content and ensures that we can view and use the website as we normally would on our screen.

But what does this interpretation mean and how does a web browser work on a technical level? In order to be able to display all resources correctly, different components perform different tasks: behind what we see, the browser’s user interface, is first of all the browser engine, which serves as a link between the user interface and the rendering engine.

The main element of the browser: the rendering engine

This module is the core component of the content presentation: by default, the engine can display HTML and XML files and images.

However, additional resources are also possible with appropriate plugins. For example, after an HTML file has been requested, the renderer parses it. This means that the engine parses the HTML data and converts it into a format that the browser can process further.

On one hand, the renderer creates the DOM structure, i.e. the structure of the tag content, and on the other hand the rendering structure, colors and other layout criteria.

The two structures are brought together in the following steps: First, the DOM tree structure or individual nodes are positioned according to exact coordinates.

Finally, the rendering structure is processed with the help of the UI backend and the website is visualized – this step is also called “Painting”. “UI” stands for “User Interface”, also called frontend, i.e. what the user finally sees on the screen.

Other browser modules

In addition to the aforementioned UI backend, which is responsible for displaying basic widgets such as windows, another module handles network calls via common protocols such as HTTP.

A JavaScript interpreter parses and executes the JavaScript code. A data store is also provided as a persistent component, which stores, for example, cookies, browser history and the local cache on the computer. This memory is processed in HTML5 as a thin web database in the browser.

Related article: What are website cookies used for?

Differences in how the browser displays data

Because there are different versions of HTML – HTML, XHTML or HTML5 – and different browsers don’t interpret them in exactly the same way, a website in Chrome sometimes looks slightly different than in Firefox.

However, the basic functions are still the same, so you’ll still see all the text, images and links – except they may be arranged and displayed slightly differently. These differences can also occur if your browser is out of date. It is therefore recommended that you update your browser regularly.