IP editing is the making of revisions by users who are not logged in to an account. The creation of articles by IP editors was removed on English Wikipedia after the Wikipedia biography controversy. This did not actually end the creation of articles by anonymous editors, because most logged-in users continue to hide their real identities behind a pseudonym. If anything, IP editors are less anonymous because they publicly reveal information about their location and/or Internet service provider.
There are often proposals to disallow all IP editing because it will reduce vandalism. It is true that much, or perhaps even most, vandalism comes from IP editors. A counter-argument is that the very fact that it is known that so much vandalism comes from IP editors means that patrollers can focus their efforts on reviewing IP edits, thereby making counter-vandalism efforts easier, not harder. Also, IP editors sometimes help revert vandalism; these editors may have little interest in going through the trouble of creating an account and logging in if they merely want to correct vandalism they stumble across once in a blue moon.