A visual node-based scripting tool that is a plug-in for Rhino. This used to be called 'Explicit History' for Rhino and a good way to describe it's usefulness is that it allows you to record a series of commands, where each step can be tied to a parameter for later adjustment.
Manufacturer McNeel
Screenshot Grasshopper Splash Screen.jpg
Entities Here we will list all the Entities.

Parameters, Components, and Data , Elk for Grasshopper , Data Tree

Interfaces Here we will list all the Interfaces.

Main Dialog

Methods Here we will list all the Methods.


Official Website
This site contains general information about Grasshopper.
Download Grasshopper
Download Grashopper here.
Digital Toolbox
Digital Toolbox is a website that investigates and educates on the use of tools in architecture.
Grasshopper Primer
The Grasshopper Primer is a comprehensive introduction to the basics of Grasshopper. On this page, you'll also find a collection of source files to get you started in Grasshopper.

Video Tutorials

Introduction to Grasshopper Webinar
An introduction to Grasshopper by David Rutten.
A massive number of video tutorials.
Design Reform
Lots of video tutorials by the guys at CASE.