Handera - - Handera develop standard and higher resolution Palm OS devices. The devices use either CompactFlash or SecureDigital cards for offline storage.
Handspring - - Handspring make the Visor and Treo ranges of Palm OS devices. Visors use a stylus as input and use Handspring's 'Springboard' slot for expansion. Treos have a small keyboard for input and use SecureDigital cards for expansion. A range of Treos have built in cellphones.
Palm - - Palm manufacture a wide variety of Palm OS devices. Recent Palm devices use SecureDigital cards or MultiMediaCards for offline storage. Palm used to own the supplier of the palm operating system (Palm OS). This is now supplied by a separate company called PalmSource.
treocentral - - Product reviews and discussion forum for Handspring Treo owners.