Prototype provides various functions for developing JavaScript applications. The features range from programming shortcuts to major functions for dealing with XMLHttpRequest.

Prototype also provides library functions to support classes and class-based objects, something the JavaScript language lacks. In JavaScript, object creation is prototype-based instead: an object creating function can have a prototype property, and any object assigned to that property will be used as a prototype for the objects created with that function. The Prototype framework is not to be confused with this language feature.