Here is a new reel on the brief question of “What is Emptiness?” in Buddhism. Obviously, this is a huge topic, but in brief, it generally refers to the idea of a “lack” or negative/absence/emptiness in the phenomena, people, events, concepts and so on which we cling to and cause us and others suffering. So, for example, our identities as a man, as a race, our nationalities and so on can be sources of great suffering and difficulties if we cling onto them too tightly.
However, there is a danger that such a view could be misunderstood only in that way as empty of identity/self, the rang-tong (empty-of-self) view. Or even worse than that, as nihilist in that nothing actually exists and so nothing matters, and we can do whatever we want. This is what Guru Padmasambhava called sacrificing conduct for the view. In this case, the wrong view.
Yet, emptiness has a more positive aspect to it, in that it is full of potentialities but also full of the Buddha Nature qualities too, such as joy, love, compassion, wisdom, bliss and so on. So depending on the causes and conditions, things can appear in beneficial ways or non-beneficial ways.
The Tibetan term for this view of the nature or reality and our essential nature/minds is zhen-tong, tong means empty and zhen means other. This view refers to the Buddha Nature as zhen tong, so the ultimate reality is not empty of itself, but empty of other, other here meaning all conditioned phenomena, self and so on. All those appearances that come and go, but which are based on clinging and separateness, cause great suffering.
For more on the view of emptiness as “empty-of-other” see articles and translations, here.
Also see the Introduction to my book Tārānatha’s Commentary on the Heart Sutra, here.