Prototype is distributed standalone, but also as part of larger projects, such as Ruby on Rails, script.aculo.us and Rico.

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.

It returns all matching elements, following the same rules as a selector in a CSS stylesheet.

If you are using the script.aculo.us extension of the core Prototype library, you can apply the "pulsate" (blink) effect as follows: In an effort to reduce the amount of code needed to run a cross-browser XMLHttpRequest function, Prototype provides the Ajax object to abstract the different browsers.

The Ajax.Request below finds the current values of two HTML form input elements, issues an HTTP POST request to the server with those element name/value pairs, and runs a custom function (called showResponse below) when the HTTP response is received from the server: Prototype also adds support for more traditional object-oriented programming.

[3] In April 2010, blogger Juriy 'kangax' Zaytsev (of Prototype Core) described at length the problems that can follow from monkey patching new methods and properties into the objects defined by the W3C DOM.