The M4 corridor is an area in the United Kingdom adjacent to the M4 motorway, which runs from London to South Wales. It is a major high-technology hub. Important cities and towns linked by the M4 include (from east to west) London, Slough, Bracknell, Maidenhead, Reading, Newbury, Swindon, Bath, Bristol, Newport, Cardiff, and Swansea. The area is also served by the Great Western Main Line, including the South Wales Main Line, and London Heathrow Airport. Technology companies with major operations located in the area include Amazon, Citrix Systems, Dell, Alcatel-Lucent, Huawei, Lexmark, LG, Microsoft, Novell, Nvidia, O2, Panasonic, SAP, Symantec.