SANE ("Scanner Access Now Easy") is a universal scanner interface. The value of such a universal interface is that it allows writing just one driver per image acquisition device rather than one driver for each device and application. So, if you have three applications and four devices, traditionally you'd have had to write 12 different programs. With SANE, this number is reduced to seven: the three applications plus the four drivers. Of course, the savings get even bigger as more and more drivers and/or applications are added. sane-backends contains documentation, several backends, scanimage command line frontend, and networking support. For other/graphical frontends take a look at sane-frontends and/or xsane.