On Wikipedia, unregistered editing, also known as anonymous editing, is the editing of Wikipedia pages while not logged in.
Some wikipedia pages require you to log in or be a registered user to edit it ... so be careful with that. While having an account has a lot of benefits, editing already existing pages without one is perfectly acceptable, and, in fact, it is very much welcomed by the Wikipedia community. There are only a few Wikipedia pages that require creating an account for editing.
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 the 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.