Information warfare is one crucial aspect of cyber security. Unlike physical targets, such as network systems or electronic devices, information warfare is aimed at manipulating what people believe to be true and thereby swaying public perceptions. A more organized and advanced form of information warfare is called cognitive warfare. It is a psychological strategy intended to gradually influence the targeted public's belief, opinion, and perception about a subject, such as an event, a politician, a government, or an ideology in general. This chapter discusses the tactics commonly used in cognitive warfare. Using the China-Taiwan relationship as an example, this chapter illustrates how such warfare is carried out.