Progressive lenses are often referred to as "no-line bifocals" or "multi-focal" lenses. They look exactly the same as single vision lenses, however, they allow you to see clearly at all distances, whether you're looking down at a book to read, or viewing the road as you drive. With progressive eyeglasses, the wearer will see clearly at all distances and will not have to suffer from those annoying bifocal lines, which are indeed visible when wearing bifocal and trifocal lenses.
As part of the natural aging process, the vast majority of people will start to need progressive lenses around 40 years old. For anyone with presbyopia (a reduction in our ability to see near-vision clearly), multifocal lenses can provide a significant visual benefit. Not to mention, progressive lenses are much more aesthetically and cosmetically appealing!