A wiki is a collaborative website, which has surpassed most people's expectations in allowing collaboration to build a knowledge resource. At the same time, the many dormant wikis show that it not as simple as installing wiki software and inviting people to contribute - a thriving wiki takes constant work by committed people.
In particular, there have been many attempts at wikis related to sustainability and international development:
- There are many Green wikis, most inactive.
- Fewer attempts at an International development wiki or Open development wiki
- There has been discussion about a Humanitarian wiki, but possibly only Appropedia is active in this area.
- Several permaculture wikis exist, mostly inactive; Appropedia's permaculture pages are active, but most of the site relates to permaculture to some degree.
- Several wikis in this area have merged to form what is now Appropedia.
- See Green wikis and development wikis for a more comprehensive look at this, with an analysis of many wikis' size and activity.