They are generally confined to the domain of the analogue copier and are being replaced as an output device on digital copiers by modern finishing units. If stapling was required, this had to be done downstream of the sorter after all pages had been collated. Finishers have a lot less limitations and therefore inherently deliver greater productivity. A finisher collates output copies by offset stacking the sets. If the sets are to be stapled then the finisher does this as each set exits the finisher and eliminates the need for separating sets by offsetting.
Some finishers also offer the option of multiple output bins.
These are not to be confused with the bins of a traditional sorter that separate sets but are used to separate jobs that may have been printed across a network from different users. Network software usually permits selection if the output bin, if multiple bins are available. The more sophisticated finishers allow insertion of pre-printed, cardboard covers. These covers can be relatively thick as they do not pass through the copier's fusing rollers. Such features therefore facilitate the production of high quality publications that may have previously been sent out to a printer.