The next generation of heterogeneous wireless access network technologies are  include such as wireless networks (WiFi and WiMax) and cellular networks (such as WCDMA and HSPA and 4G). One of the major issues in heterogeneous wireless network design, support for mobile users is vertically integrated handover. handover process between different wireless technology, called vertical handover. The wireless technology of different features, services, pricing, and offer different regional coverage. Vertical handover can be combined with the benefits of mobile networks to obtain user satisfaction and improve efficiency, can be used. So concepts and review the measures taken are necessary. The main purpose of this article we discribe the basic concepts related to handover, classification, algorithms, protocols, and features favorable factors in handover for Next Generation Networks.