A being, in the most general sense, is anything that is alive.
In philosophy, a being is anything that can be said to be. Ontology is the philosophical study of being. See also categories of being and "I think, therefore I am".
In linguistics, "to be" is a copula.
Being in continental philosophy and existentialism
Some philosophers deny that the concept of "being" has any meaning at all, since we only define an object's existence by its relation to other objects, and actions it undertakes. The term "I am" has no meaning by itself; it must have an action or relation appended to it. This in turn has led to the thought that "being" and nothingness are closely related, developed in existential philosophy.
Existentialist philosophers such as Sartre, as well as continental philosopers such as Hegel and Heidegger have also written extensively on the concept of being, distinguishing between the being of objects (being in itself) and the being of people (Geist in Hegel, Dasein in Heidegger, and being-for-itself and being-for-others in Sartre).
Further reading
See also