What Is a Web Application?

Improve your understanding of web-based application programs

Wondering what a web application is? Believe it or not, you've probably used one before without even realizing it.

Just as a mobile app exists on a mobile device, a web application (or "web app" for short) is any computer program that performs a specific function by using a web browser as its client. The application can be as simple as a message board or a contact form on a website, or it can be as complex as a word processor or multi-player mobile gaming app that you download to your phone.

Illustration of web apps.
Ade Akinrujomu / Getty Images

What Is a Client?

In a client-server environment, "client" refers to the host program a person uses to run an application. A client-server environment is one in which multiple computers share information from a database. Where the server hosts information, the "client" is the application used to access the information.

What Are the Benefits of Using Web Applications?

A web application relieves the developer of the responsibility of building a client for a specific type of computer or operating system, so anyone can use the application along as they have internet access. Since the client runs on a web browser, the user could be using a PC or a Mac. They could be using Internet Explorer, Chrome, or Firefox, though some applications require a specific web browser.

Web applications commonly use a combination of server-side script (ASP, PHP, etc) and client-side script (HTML, Javascript, etc.). The client-side script deals with the presentation of the information, while the server-side script deals with all the hard stuff like storing and retrieving the information.

How Long Have Web Applications Been Around?

Web applications have been around since before the World Wide Web went mainstream. For example, Larry Wall developed Perl, a popular server-side scripting language, in 1987. That was seven years before the internet really started gaining popularity outside of academic and technology circles.

The first mainstream web applications were relatively simple, but the late 90s saw a push toward more complex web applications. Nowadays, millions of Americans use web applications to file income taxes online, perform online banking tasks, share posts on social media, communicate with friends and family, and more.

How Have Web Applications Evolved?

Most web applications are based on the client-server architecture, where the client enters information and the server stores and retrieves information. Email is a good example of this, with services like Gmail and Microsoft Outlook offering web-based email clients.

More and more web applications have been developed to handle functions that normally would not require server access. For example, Google Docs is a web application that can act as a word processor, storing information in the cloud and allowing you to "download" the document onto your personal hard drive.

If you've been using the web long enough, you have seen how sophisticated web applications have become. Much of that sophistication is because of AJAX, which is a programming model for creating more responsive web applications.

G Suite (formerly Google Apps) and Microsoft 365 are other examples of the newest generation of web applications. Mobile applications that connect to the internet (such as Facebook, Dropbox, and various banking app) are also examples of how web applications have been designed for the increasing share of the mobile web in global internet traffic.