A binary number that uniquely identifies a host computer connected to the Internet. The IP packet header provides an originating address field so that a host can identify itself as the originator of a packet. The IP packet header also provides a destination address field so that an originating host can identity the target host for which a packet is intended. Based on that information, the Internet routers can act to deliver the packet to the target host, which can respond to the originating host, as appropriate. All IP addresses are written in dotted decimal notation. An IPv4 address, for example, comprises 4 fields separated by dots and expressed as xxx.xxx.xxx.xxx, with each field given a value in decimal notation of 0