Web browser

Key takeaways

Web browser belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Web browser to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Web browser from memory before moving on to harder problems.

Reference excerpt

A web browser, often abbreviated as browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen. Browsers can also display content stored locally on the user's device. Browsers are used on a range of devices, including desktops, laptops, tablets, smartphones, smartwatches, smart televisions and consoles. As of 2026, the most used browsers worldwide are Google Chrome (~69% market share), Safari (~16%), Edge (~5%), Firefox (~2%), Samsung Browser (~2%), and Opera (~2%). As of 2023, an estimated 5.4 billion people had used a browser.

Function

The purpose of a web browser is to fetch content and display it on the user's device. This process begins when the user inputs a Uniform Resource Locator (URL), such as https://en.wikipedia.org/, into the browser's address bar. Virtually all URLs on the Web start with either http: or https: which means they are retrieved with the Hypertext Transfer Protocol (HTTP). For secure mode (HTTPS), the connection between the browser and web server is encrypted, providing a secure and private data transfer. For this reason, a web browser is often referred to as an HTTP client or a user agent. Requisite materials, including text, style sheets, images, and other types of multimedia, are downloaded from the server. Once the materials have been downloaded, the web browser's engine (also known as a layout engine or rendering engine) is responsible for converting those resources into an interactive visual representation of the page on the user's device. Modern web browsers also contain separate JavaScript engines which enable more complex interactive applications inside the browser. A web browser that does not render a graphical user interface is known as a headless browser. Web pages usually contain hyperlinks to other pages and resources. Each link contains a URL, and when it is clicked or tapped, the browser navigates to the new resource. Most browsers use an internal cache of web page resources to improve loading times for subsequent visits to the same page. The cache can store many items, such as large images, so they do not need to be downloaded from the server again. Cached items are usually only stored for as long as the web server stipulates in its HTTP response messages. A web browser is not the same thing as a search engine, though the two are often confused. A search engine is a website that provides links to other websites and allows users to search for specific resources using a textual query. However, web browsers are often used to access search engines, and most modern browsers allow users to access a default search engine directly by typing a query into the address bar.

History

The first web browser, called WorldWideWeb, was created in 1990 by Sir Tim Berners-Lee. He then recruited Nicola Pellow to write the Line Mode Browser, which displayed web pages on dumb terminals. The Mosaic web browser was released in April 1993, and was later credited as the first web browser to find mainstream popularity. Its innovative graphical user interface made the World Wide Web easy to navigate and thus more accessible to the average person. This, in turn, sparked the Internet boom of the 1990s, when the Web grew at a very rapid rate. The lead developers of Mosaic then founded the Netscape corporation, which released the Mosaic-influenced Netscape Navigator in 1994. Navigator quickly became the most popular browser. Microsoft debuted Internet Explorer in 1995, leading to a browser war with Netscape. Within a few years, Microsoft gained a dominant position in the browser market for two reasons: it bundled Internet Explorer with its popular Windows operating system and did so as freeware with no restrictions on usage. The market share of Internet Explorer peaked at over 95% in the early 2000s. In 1998, Netscape launched what would become the Mozilla Foundation to create a new browser using the open-source software model. This work evolved into the Firefox browser, first released by Mozilla in 2004. Firefox's market share peaked at 32% in 2010. Apple released its Safari browser in 2003; it remains the dominant browser on Apple devices, though it did not become popular elsewhere. Google debuted its Chrome browser in 2008, which steadily took market share from Internet Explorer and became the most popular browser in 2012. Chrome has remained dominant ever since. In 2015, Microsoft replaced Internet Explorer with Edge [Legacy] for the Windows 10 release. In 2020, this legacy version was replaced by a new Chromium-based version of Edge. Since the early 2000s, browsers have greatly expanded their HTML, CSS, JavaScript, and multimedia capabilities. One reason has been to enable more sophisticated websites, such as web apps. Another factor is the significant increase of broadband connectivity in many parts of the world, enabling people to access data-intensive content, such as streaming HD video on YouTube, that was not possible during the era of dial-up modems. Starting in the mid-2020s, browsers with integrated artificial intelligence (AI) capabilities, known as AI browsers, have become increasingly common. This includes both new entrants to the browser market, such as Perplexity Comet and ChatGPT Atlas, and established browsers that added AI features, such as Chrome with the Gemini chatbot and Edge with the Copilot chatbot.

Features The most popular browsers share many features. They automatically log users' browsing history, unless the users turn off their browsing history or use the non-logging private mode. They also allow users to set bookmarks, customize the browser with extensions, and manage their downloads and passwords. Some provide a sync service and web accessibility features.

Common user interface (UI) features:

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Web browser

Start with the simplest possible case. Write down what Web browser claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Web browser before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Web browser ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Web browser

In research: Web browser appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Web browser in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Web browser is common in secondary-school and first-year university syllabi. It links to neighbouring topics English inventions, Web browsers, so understanding it makes those chapters shorter.
In everyday life: Look for Web browser outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Web browser in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Web browser means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Web browser out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Web browser in simple terms?

A web browser, often abbreviated as browser, is an application for accessing websites. When a user requests a web page from a particular website, the browser retrieves its files from a web server and then displays the page on the user's screen.

Why does Web browser matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Web browser?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Web browser.