The vast majority of modern cameras use autofocus. However, a handful of cameras offer manual focus only, notably Leica M rangefinders, and almost all cameras allow you to switch to a manual focus mode. There’s also a growing marked for affordable ‘manual’ lenses with excellent optical performance, compact size and relatively low cost, driving largely by Chinese makers.
Manual focus might sound like a chore, but it has some significant advantages. It’s more or less essential if you want to make the most of depth of field, for example, which can often mean focusing between two objects rather than on one or the other, or hyperfocal focusing, where you want both nearby objects and distant backgrounds sharp at the same time. It’s also handy for ‘zone focusing’ in shoot-from-the-hip style street photography, where you want an instant shutter response.
Older ‘manual’ lenses are ideally suited to this because they have detailed distance scales on the focus ring and depth of field index markers to indicate the near and far limits of depth of field. Modern lenses are less effective because their manual focus rings have a shorter travel, the distance scales are compressed and less precise (many lenses don’t even have them) and depth of field marker are not often used.
Depth of field index markers can’t be used on zoom lenses because the depth of field changes with the zoom setting. You only find them on fixed focal length, or ‘prime‘ lenses.