Web Applicationweb application or webapp is an application that is accessed via a web browser over a network such as the
Internet or an intranet. It is also a computer software application that is coded in a browser-supported language (such as
HTML, JavaScript, Java,PHP, etc.) and reliant on a common web browser to render the application executable.
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.
The web interface places very few limits on client functionality. Through Java, JavaScript, DHTML, Flash and other technologies
Application-specific methods such as drawing on the screen, playing audio, and access to the keyboard and mouse are all possible, etc.
General purpose techniques such as drag and drop are also supported by these technologies. Web developers often use
client-side scripting to add functionality, especially to create an interactive experience that does not require
page reloading.
Recently, technologies have been developed to coordinate client-side scripting with server-side technologies such as
PHP.
Ajax, a web development technique using a combination of various technologies, is an example of technology which creates a more interactive experience.
Struktur WebappApplications are usually broken into logical chunks called
"tiers", where every tier is assigned a role. Traditional applications consist only of 1 tier, which
resides on the client machine, but web applications lend themselves to a
n-tiered approach by nature. Though many variations are possible, the most common structure is the three-tiered application. In its most common form, the
three tiers are called
presentation, application and storage, in this order.
A web browser is the first tier (presentation), an engine using some dynamic Web content technology (such as ASP, ASP.NET, CGI, ColdFusion, JSP/Java, PHP, Perl, Python, Ruby on Rails or Struts2) is the middle tier (application logic), and a database is the third tier (storage).
The web browser sends requests to the middle tier, which services them by making queries and updates against the database and generates a user interface.
sumber & more detail: http://en.wikipedia.org/wiki/Web_application