These people not only wear costumes, but also interact with the guests by improving their acting expertise, social skills, and theatrical expertise as part of their jobs. Like the Atmosphere Characters, they are assisted by a character host at all times; sometimes, they interact (in character, of course) with their host. The hosts also, in some cases, serve as the characters' bodyguards if a character has a bad encounter with an unruly or inappropriate guest.
An example of a change for the better came in the 1980s, when park executives (and Michael Eisner) decided to change the Mad Hatter from an atmosphere character into a face character so that they would be allowed to better interact with guests.
Face characters also, at one point, went on rides and attractions with park guests (they still can, as evidenced by this video), and the face characters normally stick to a script from their respective films, only taking liberties when necessary to have better conversations with guests.
The most common misconception of the face characters is that they often are for children, but as countless YouTube videos (such as those of guest Tommy Des Brisay) show, this is not the case. Guests like Tommy can also invite face characters to join them for lunch and dinner at any of the restaurants in the parks.
Because of child labor laws, all the characters that would normally be played by young children or teenagers (like Alice, Wendy Darling, John Darling, Michael Darling, Hiro Hamada and the Lost Boys, for example) are instead played by full-grown adults.