One of the ways an encyclopedia is an ideal project for crowdsourcing is that it is strongly modular: it can be broken down into many individual pieces of work which do not depend on each other.
It may seem, though, that the whole process depends on detailed planning to create a structure in which crowdsourcing will be successful. In particular, it might seem that the policies and guidelines that define good work have to exist before people start the work.
Evolving policies and standards
In fact, Wikipedia did not turn out like this. Policies and guidelines are created by the same process as the articles: public editing and discussion to consensus, often seeded by a very short statement. These policies and standards have evolved with the articles.
In the course of writing the best content, or handling the most contentious disputes, the community has reached consensus on points of style, scope, user conduct and so on. This consensus can then be cited in similar debates or written up as a policy or guideline. Once an article is badged as a 'featured article', representing the community’s best work, it can be used as a model for the development of related articles. So the role of good content in shaping policy is as important as policy’s role in shaping content.
Goals and vision
Wikimedia has as its vision statement:
"a world in which every single human being can freely share in the sum of all knowledge."
This statement, which reflects both the long-term focus of the project and the moving target it is aimed at, is known by all active contributors and cited as a guiding principle in on-wiki discussions.
Wikipedia’s role is to be a general-audience encyclopedia in the same sense as Britannica. This goal is literally tangible for those generations who grew up with print encyclopedias. Having an “old-fashioned” goal is a plus: projects with too novel a goal restrict their own growth because not enough people can grasp the goal and decide whether it is being achieved (Mako-Hill, 2012).
The Wikimedia and Wikipedia goals are made more concrete for contributors when they hear of people benefiting who were previously information-poor, such as the recipients of the one laptop per child project or the use of Wikipedia by schoolchildren in the townships of South Africa.