Usually, it is normal to see black dots. Don't worry about that. It is just a natural occurrence. Most of us will experience this throughout our lives. Sometimes when we are too tired, we will see black dots. While if we stop moving your eye balls, the black dots may move around slowly. But if we try to focus on them, they may move out of the way quickly. Most people choose to ignore them. But if you see a lot of black spots suddenly, it may be a sign of infection, hemorrhaging, inflammation or retinal tears. You have to get your eyes checked by your doctor.
Black dots can be called floaters or black spots. Floaters look like spots, strands or squiggly lines. Black dots are more apparent when you look at a blank surface or the blue sky. There are various causes of black dots, while they do not cause serious problems for most people. But some damages to eyes can causes material to enter the vitreous humour. When you see a flurry of black dots, it may mean the detachment of the retina. Your peripheral vision may be impaired if you not treat it. I suggest you to seek medical care immediately and treat it within two or three days.