Panpsychism is the view that all matter in the universe contains elements of mental properties or consciousness. This is not to say that panpsychism believes that all matter is alive or even conscious but rather that the constituent parts of matter are composed of some form of mind and are sentient.
Panpsychism claims that everything is sentient and that there are either many separate minds, or one single mind that unites everything that is. The concept of the unconscious, made popular by the psychoanalysts, made possible a variant of panpsychism that denies consciousness from some entities while still asserting the ubiquity of mind.
Panexperientialism, as espoused by Alfred North Whitehead is a less bold variation, which credits all entities with phenomenal consciousness but not with cognition, and therefore not necessarily with fully-fledged minds.
Panprotoexperientialism is a more cautious variation still, which credits all entities with non-physical properties that are precursors to phenomenal consciousness (or phenomenal consciousness in a latent, undeveloped form) but not with cognition itself, or with conscious awareness.
Five quick points of panpsychism:
1) Modern panpsychism accepts the reality of qualia; to posit consciousness in all things, one must first posit consciousness in oneself.
2) According to modern panpsychism, consciousness simpliciter not self-consciousness, emotion, desire, belief, cognition, or even really awareness as we would understand it, but bare subjectivity is a fundamental force of our universe, analogous to gravity and (especially) electromagnetism.
3) The analogy to gravity runs as follows: wherever there is mass, however inconceivably negligible, there is gravitation. Unlike gravity, however, consciousness does not simply accrete; the bare subjectivity of matter remains discrete and at its lowest natural level (subatomic scale? quark scale? Planck scale?) until organized into a conscious system, and hence gains nothing from merely being glommed together as a grain of sand, pebble, rock, mountain, planet, star, etc.
4) The analogy to electromagnetism runs as follows: while electromagnetism is a fundamental force (as Wikipedia says, the one responsible for practically all the phenomena encountered in daily life, with the exception of gravity” ), its most interesting effects occur when complex conditions obtain, e.g., an electrical circuit. Electromagnetism is undoubtedly present in an electron or rock, but not the way it is in a thermostat, hair dryer, computer, or human brain; these latter constitute electromagnetic systems in a way the electron and rock do not. Likewise, modern panpsychism says, with consciousness. (Indeed, perhaps, in some Spinozan way, consciousness is identical to electromagnetism, though modern panpsychism certainly isn’t committed to this.)
5) In light of the above, one might state the modern panpsychist position as follows: consciousness is present in everything, but not everything is a conscious system.