Wikipedia:Welcome unregistered editing
On Wikipedia, unregistered editing, also known as IP editing and incorrectly as "anonymous editing", is the editing of Wikipedia pages while not logged in. When such an edit is made, the IP address associated with the present connection will be permanently recorded in the edit history of the page that has just been edited.
While having a username has a lot of benefits, editing already existing pages without one is perfectly acceptable, and in fact, is very much welcomed.
Editing is a blessing to Wikipedia
The source of edits concerns Wikipedia only in terms of how it affects their quality and their legal status; therefore, unregistered editing should be encouraged whether done by newcomers, or by even old hands wishing a return for renewal of the prime unregistered editor experience.
Restricting individuals' unregistered edits should be a last resort
Even those who have transgressed should be welcome to edit as an unregistered user, so long as they are able to do so civilly. The sanction of withdrawing such ability to contribute should only be enacted when the person has not responded to milder forms of rebuke and restriction of privileges. Even then it should always be limited in time.