Answer - 1. Handheld devices are palm tops and cellular telephones with connectivity to a network. 2. These devices are of limited size which leads to limited applications. 3. They use a memory 512KB to 16MB as a result the operating system and applications must use the memory efficiently. 4. The speed of the processors is only a fraction of speed of the PC processors and for faster processors larger battery is required. 5. These devices use very small display screens so reading mails and browsing must be condensed to smaller displays.