What is a wireless AC router?

A wireless AC router is a local area network device that operates using the 802.11ac communication standard to provide Wi-Fi service, allowing users to connect wireless and mobile devices to private networks and the Internet. It remains the current standard used in all new wireless devices as of 2015

The 802.11ac standard replaces its 802.11n predecessor that was established in 2007. It offers faster data transfer speeds and operates better at longer ranges than the previous standard. It also provides backwards compatibility with all previous 802.11 wireless standards so all older devices work with it. However, an older device remains limited to the maximum speed of the standard on which it operates.