CAT6 are 4 pair cables which allow for 10 Gigabit Ethernet speeds (10GBASE-T), unlike CAT5e's maximum of 1 Gigabit Ethernet. CAT6 also allows for two-way communication for each pair of wires, which leads to faster perceived speed. If you need a fast internal network and do not need cable lengths of more than 128 feet (longer lengths are 1 Gigabit), then CAT6 is the best choice. CAT6 is fully backwards compatible with CAT5e, CAT5 and CAT3 equipment.