1. Suffering through natural calamities
2. Suffering through one’s own ignorance or one’s own laziness. This is man-made
3. Suffering due to karma where you don’t even know what the root cause of this kind of suffering is. It goes beyond the current framework of time. You have to go very much forward in the realm of consciousness to find out why this suffering is there now. There is no apparent cause for it. But the cause is hidden somewhere in the past. You need to dig into that cause
These are the three types. All these can be avoided, and rectified.