Yes I understand the definition of reactive power. It is the power that flows back and forth on transmission lines and does not do work(correct me). My question is, is reactive power useful? In what case reactive power has to be minimized as low as possible? I read an article about the importance of reactive power that it is required to maintain the voltage to deliver active power through transmission lines. Isn't p.f. 1, in other words zero reactive power, always what we want?