Back on the End of Suffering, I quoted the Yoga Sutra on ignorance.
2v5: Ignorance is perceiving the non-eternal as eternal, the impure as pure, suffering as happiness, and the non-Self as the Self.
The short way of saying this is ignorance of our true nature or ignorance of reality.
But another way to say ignorance is lack of knowledge, lack of direct experience of our true nature. This leads to the mistakes in the sutra.
In other words, ignorance is an absence. It’s a shadow. It doesn’t actually exist. In fact, it’s lack of awareness of our true existence as the infinite.
The light of consciousness removes the shadow and brings us knowledge of our true nature. And that is the end of ignorance.