Galaxy Zoo was an online project to classify the types of galaxies in large surveys, a project which spawned subsequent Galaxy Zoo variants as well as other crowdsourcing unrelated science and scholarly projects to assist in classifying large collections of material.
The original Galaxy Zoo operated from 2007 to 2009 to classify objects photographed by the Sloan Digital Sky Survey, displaying the object to the website-visitor, prompting for input as to whether the object appears to be elliptical or spiral as well as to the direction of the spirals. They are generally in the z=0.06-0.08 range. Tens of thousands of volunteers classified millions of galaxies. Its survey results have been published and interesting galaxies were discovered.
Galaxy Zoo 2 was the first follow-on galaxy-classification project and there have been more since, including one to classify galaxies in DECaLS data and another to classify galaxies in a mock catalog drawn from the Illustris Project. The name Zooniverse encompasses all the crowd-sourced science and scholarly projects that Galaxy Zoo spawned.