A scripting language, also referred to as an extension language, is a type programming language that executes various software applications. Scripting languages are descendants of the Job Control Language, an early language used by corporations to automate the execution of a series of tasks. This automation is called batch processing.
Languages used to control batch processing, called batch languages, are the earliest forms of a scripting language. Since the 1950s, batch languages have been used as a way to perform high-level yet rote business functions, such as billing and reports. Batch languages are usually tied to a particular shell, or user interface. Popular shells for batch languages include Cocoa®, various UNIX® shells, and MS-DOS®.
There are many purposes for a scripting language. One very important purpose of such a language is to serve as a glue code. A glue code is a code used to bind together various programs and applications unrelated to each other.
Scripting languages are also used in build automation for graphical user interfaces (GUI). A GUI allows users to interact with an interface designed with images, buttons, and menus instead of command line operations. A modern day computer desktop is a good example of a GUI. A scripting language facilitates certain functions of a GUI, such as printing and file renaming.
Many web applications are also written in a scripting language. One of the more recognizable web applications is a web browser. In its most basic form, a web browser allows the user to view dynamic web pages and move from page to page. Some examples of popular scripting languages used to build and design websites include JavaScript®, XUL™, Ajax, VBScript®, and XLST.
In order to create dynamic and interactive applications on the Internet, scripting languages must be used. One popular scripting language used for this purpose is PHP. PHP builds on HTML by providing specific instructions for HTML blocks of code. In other words, HTML "comes to life" when PHP is embedded. PHP is primarily used as a server-side script which means it acts as a mediator between the front end of a website and its back end databases and data stores.
Scripting languages can also be utilized as domain-specific languages. A domain-specific language is tailored to execute programs or applications for a specific domain problem or domain solution. For example, SQL is used to facilitate database queries, Logo is used to teach children how to program, and regular expressions are used by a variety of scripting languages to process text-based files and documents.