Visitors can view and edit most of pages on Wikipedia (except special pages and main page), the possibility of changing the pages is one of the basic concepts of Wikipedia. Visitors can edit articles or pages (except special pages and the homepage) to complete, even without opening an account. Users (anonymous and registered) can test the Wiki syntax in their user page or the sandbox. (more ...)
Wikipedia is an encyclopedia, all your publications on the Wikipedia can be modified and distributed freely by the visitors or users (according the GNU-FDL license). If you do not want your writing to be modified and distributed, do not post them here.
Wikipedia is not a dictionary, for definitions of words, see the Wiktionary (mg).
You can create an account on Wikipedia, the fields are mandatory to fill in the username and password. It is difficult to change a user name, and it is impossible to delete an account already created. Open an account on Wikipedia presents some advantages : For example, you can become administrator or bureaucrat on wikipedia, or steward on all wikis ; thing you can not do by being anonymous (IP) over the user name cache your IP. (more ...)