Emptiness is the Buddhist word most likely to be misheard. Told that things are empty, and that the self is empty too, it is easy to hear a verdict: nothing is really there, so nothing really matters, and the calm on offer is the calm of someone who has stopped caring.
Hear the word the way the tradition uses it and it turns round, because it rests on an idea about connection. Dependent origination (Pratītyasamutpāda) is the structural insight beneath all the rest: everything arises from what came before it, and in turn shapes what follows. Nothing exists independently or permanently. It is the basis for both impermanence and no-self.
Emptiness (Śūnyatā) is its close pair, and that is what the word means: not that nothing exists, but that nothing exists on its own, by itself, apart from the web that holds it. Empty, in that sense, is the opposite of absent. It is the word for how much of everything else is in each thing.
Driving this conditioned arising is karma, intentional action and its fruit, the choices that condition what comes next. Buddhism holds karma without a permanent self to carry it; its full treatment, with that difference drawn out, lives on Karma.
Later Buddhist thought gave the idea its most beautiful image: Indra's net, an infinite net stretching in every direction, a jewel at each knot, every jewel reflecting all the others. Touch one, and the whole net trembles. The Zen teacher Thich Nhat Hanh gave it a modern word, interbeing. A sheet of paper, he wrote, holds the cloud that became the rain, the sun, the forest, the logger and the bread that fed him: to be is to inter-be. The plainest secular name for the same insight is systems thinking. You cannot understand a part in isolation, because what a thing is includes its relationships.