Online micro-volunteering is also an example of virtual volunteering and crowdsourcing, where volunteers undertake assignments via their PDAs or smartphones. These volunteers either aren't required to undergo any screening or training by the nonprofit for such tasks, and do not have to make any other commitment when a micro-task is completed, or, have already undergone screening or training by the nonprofit, and are therefore approved to take on micro-tasks as their availability and interests allow. Online micro-volunteering was originally called "byte-sized volunteering" by the Virtual Volunteering Project, and has always been a part of the more than 30-year-old practice of online volunteering.[9] An early example of both micro-volunteering and crowdsourcing is ClickWorkers, a small NASA project begun in 2001 that engaged online volunteers in scientific-related tasks that required just a person's perception and common sense, but not scientific training, such as identifying craters on Mars in photos the project posted online; volunteers were not trained or screened before participating.