Coral reefs are the most diverse ecosystems on the Earth. They are habitat for many species of marine organisms, and offer a plethora that benefit to human life. Coral reef brings in enormous funds to coastal countries through tourism, fishing, and discoveries of new biochemical and drugs. Coral reef, together with mangrove ecosystems and seagrass ecosystems, provide natural coastal protection. Ecologically, coral reefs are the feeding, nursery and spawning ground for many marine organisms. Coral reef are sensitive to physical and chemical environmental factors, that can become limiting factors. Physical environmental factors that have significant role in the development of coral reefs are temperature, depth, salinity, and turbidity. Coral reef is a habitat for many species of aquatic microflora and macrophyta, and many other species of marine flora. Coral communities consist of coral animals that are reef makers or hermatypics. The Scleractinia is the most dominant reef makers. Population diversity in the coral reef ecosystems is very high. Primary productivity of coral reef is higher than other ecosystems, such as seagrass and tropical forest ecosystems. Coral reefs suffer from a lot of pressure, about 75 percent of the world’s reefs face threats from pollution, habitat destruction, overfishing and, increasingly, a changing climate that increases temperatures, sea level, and acidity in the oceans. Degradation of coral reef can be caused by anthropogenic and natural disturbance. Anthropogenic disturbance are coral rock extraction, sedimentation, waste, eutropication, and fisheries. Coral reef are also suffer by natural pressure. The natural pressure are disease, acanthaster outbreak, coral bleaching, and global climate change. Some previous studies showed that rising global temperatures, increasing oceanic CO2, and other impact of climate change were affecting coral reef health in a negative way, and if CO2 emissions continue to increase at the current rate, there will most certainly reductions in the area and diversity of coral reefs in the future.