All this is suffering. I gnorance Craving or desire is like a great tree having many branches. There are branches of greed, of ill will and of anger. The answer is that the tree of craving is rooted in ignorance. It grows out of ignorance.
Ignorance is the inability to see the truth about things, to see things as they really are.
There are many truths about the world which people are ignorant of because of the limitations of their understanding. Science has shown, for instance, that there are sounds that people are unable to hear and waves of light which they are unable to see. People would be totally unaware of radio waves, or ultraviolet light rays if special instruments had not been developed to enable them to observe these things. So long as people remain ignorant of things about the world in which they live, they suffer from all kinds of misunderstandings and delusions. When people develop their minds and acquire wisdom through study, careful thought and meditation they will see the Truth.