For Foucault, every relation between forces is a "power relation." Power is not essentially repressive. It is practiced before it is possessed, and it passes through the hands of the mastered no less than through the hands of the masters. Therefore we should ask: "How is it practiced?" It is a physics of abstract action. (Deleuze, Foucault, p. 72) 

"Power has its principle not so much in a person as in a certain concerted distribution of bodies, surfaces, lights, gazes; in an arrangement whose internal mechanisms produce the relations in which the individuals are caught up." (Discipline and Punish, p.202) (see also spectacle)

"Power must be understood... as the multiplicity of force relations immanent in the sphere in which they operate and which constitute their own organization; as the process which, through ceaseless struggles and confrontations, transforms, strengthens, or reverses them." (History of Sexuality, Vol 1, p. 26) 

According to Deleuze, power is local because it is never global, but it is not local or localized because it is diffuse" (Foucault, p. 26)

note relation between power, knowledge, and pleasure.

For Bertrand Russell, "Scientific thought is essentially power thought--the sort of thought whose purpose, conscious or unconscious, is to give power to its posessor." For Foucault, knowledge and truth are inseparable from power. If knowledge consists of linking the visible and the articulable, power and knowledge presuppose and constitute each other.