IEEE 802.11ac-2013 is an amendment to IEEE 802.11, approved on January 7, 2014, that builds on 802.11n. Changes compared to 802.11n include wider channels (80 or 160 MHz vs. 40 MHz) in the 5 GHz band, more spatial streams (up to 8 vs. 4), higher order modulation (up to 256-QAM vs. 64-QAM), and the addition of Multi-user MIMO (MU-MIMO). 
As of October 2013, high-end implementations support 80 MHz channels, three spatial streams, and 256-QAM, yielding a data rate of up to 433.3 Mbit/s per spatial stream, 1300 Mbit/s total, in 80 MHz channels in the 5 GHz band.