4G refers to the next generation of wireless technology that promises higher data rates and expanded multimedia services. It is defined as a fully IP-based integrated system providing 100 Mbps outdoors and 1 Gbps indoors, with quality of service and security, offering customized personal services anywhere through seamless interoperability using technologies like OFDM, MIMO and IPv6. Research is ongoing to build 4G networks through approaches like lower prices, more spectrum coordination, and standardization while addressing issues like security, lack of standards and wireless spam.