Web applications are popular due to the ubiquity of web browsers, and the convenience of using a web browser as a client, sometimes called a thin client. The ability to update and maintain web applications without distributing and installing software on potentially thousands of client computers is a key reason for their popularity, as is the inherent support for cross-platform compatibility. Common web applications include webmail, online retail sales, online auctions, wikis and many other functions.
One of the most basic types of Web application development involves e-commerce sites. This is the kind of website you see when you shop online. Designers of these sites must anticipate all kinds of unusual customer behavior, as well as heavy traffic, while keeping the server and "shopping cart" up and running.
The ease of online shopping has created an "always-on" environment in which people can shop at all times of the day and night, wherever they are. E-commerce sites must be available to accept orders and money no matter what time it is at corporate headquarters. Web application development can lend itself specifically to e-commerce site creation, but the programmer would do well to keep the 24/7 mentality of potential customers in mind.