Among the diverse forms of malware, Botnet is the serious threat which occurs commonly in today’s cyber attacks and cyber crimes. Botnets are designed to perform predefined functions in an automated fashion, where these malicious activities range from online searching of data, moving files sharing channel information to DDoS attacks against critical targets, click fraud etc. Botnet detection has been an interesting research topic related to cyber-threat and cyber-crime prevention. In this survey paper we provide a brief look at how existing botnet research, the evolution and future of botnets, as well as the goals and visibility of today’s network intersect to inform the field of botnet technology and defense.