You are welcome to contribute a short start of a new article, called a "stub", of about 150-250 words usually.
Stubs may be written solely to introduce the topic of the article in such a way that you or other authors can use the stub as written to continue on to develop the article. Include a definition or description of the topic.
If you write a stub-length or slightly longer piece that is self-contained and serves as a good overview or summary of the topic, classify it as a Developing article. Include a definition or description of the topic. Such an article should be serviceable as an entry in a traditional desktop reference such as the Columbia Encyclopedia.
Some people believe that stubs encourage others to help "build the web." Many people can write excellent stubs or short developing articles even when they don't have the knowledge to expand them. So if you feel tempted to "turn a red link blue" with a stub, feel free.