Panpsychism is an umbrella term for philosophical theories of mind where everything, has a mind of mind-like quality. On these views, experience is a fundamental property of matter, like charge or mass. In slogan form: mind and matter are inseparable, or everything is conscious.

Some mental states are non-conscious states, meaning they are necessarily non-experiential. Examples include the mental states associated with tasks involving implicit memory like breathing or blinking.

Ned Block distinguished between two types of conscious states. Some conscious mental states are access conscious (A-conscious) states, meaning they are available for cognition independent from your experience of them. For example, your belief in some proposition doesn't start and stop depending on whether you are conscious of it. Other mental states are phenomenally conscious (P-conscious) states, meaning they are necessarily experiential. A mental state is P-conscious if, and only if, there is something it is like to be in that mental state. An entity is P-conscious if, and only if, it possesses P-conscious mental states.

Most panpsychist views don't argue that ordinary objects such as coffee tables or rocks are P-conscious. But they do hold that the matter that makes up ordinary objects is P-conscious. That is, although fundamental particles lack complex thoughts, feelings, a complex sense of self-awareness, and other traits colloquially associated with animal consciousness, an electron (for instance) still has some basic kind of experience.

One prominent version of panpsychism is Bertrand Russell's dual-aspect monism (aka neutral monism), which says, roughly speaking, that the "stuff" composing reality comes in one neutral flavor—neither physical nor mental—and has two mutually-exclusive, irreducible aspects: physical properties (objective, relational) and phenomenal properties (subjective, intrinsic).