What do u mean by hypoxia..?

Hypoxia, in medicine, condition of the body in which the tissues are starved of oxygen. In its extreme form, where oxygen is entirely absent, the condition is called anoxia.
There are four types of hypoxia:
(1) the hypoxemic type, in which the oxygen pressure in the blood going to the tissues is too low to saturate the hemoglobin.
(2) the anemic type, in which the amount of functional hemoglobin is too small, and hence the capacity of the blood to carry oxygen is too low.
(3) the stagnant type, in which the blood is or may be normal but the flow of blood to the tissues is reduced or unevenly distributed.
(4) the histotoxic type, in which the tissue cells are poisoned and are therefore unable to make proper use of oxygen. Diseases of the blood, the heart and circulation, and the lungs may all produce some form of hypoxia.