Wire-EDM is an important technology, which demands high-speed cutting and high-precision machining to realize productivity and improved accuracy for manufacturing hard materials. High cost of WEDM tool, compared to traditional machining, has forced us to operate these machines as efficiently as possible in order to reduce production cost and to obtain the required reimbursement. To achieve this task, different machining parameters should be selected such that optimal value of their response variables can be obtained. In past decades, intensive research work had been carried out by different researchers for optimization of WEDM responses using various optimization techniques like Taguchi method, RSM, GRA, GA, SA, PSO etc. The review work on such a large scale was not attempted earlier by considering many machining parameters, machining responses and optimization techniques at a time, and finally lists down certain areas that can be taken up for further research in the field of improvement and optimization for WEDM process. Hence, this book may become the ready information at one place and it may be very useful to the subsequent researchers to decide their direction of research.