A population of organisms which is in danger of becoming extinct because there are only a few left, or because they are jeopardized by the changing environmental conditions or predation parameters. Of course this animal are also threatened by human activities, like deforestation, which decreases the amount of food, water or living space. The International Union for Conservation of Nature (IUCN) has calculated that 40 percent of all organisms are endangered, an evaluation helped with the list of species from 2006. That is why many nations have laws for protecting and conserving endangered species such as prohibition of hunting, creating preservations where the animals and plants can thrive, or the restriction of land development so that it cannot be affected by any human activity. But still, the problem remains because many of the species threatened of extinction are not included into those laws. The criteria for putting these species under protection and placing them on the list of endangered, or removing them from that list, are not the same everywhere and that is where the problems can begin. People decide which of them are worth saving and which are undesired or unimportant. Although they are only a few of some species left, no one takes any notice or responsibility and many of them vanish without the people even noticing or knowing. Each of these endangered species are given a conservation status, an indicator that tells us the probability that species has of extinction. Also, there are different categories for threatened species, a general term used by IUCN. They are: extinct(there are no more remaining species), extinct in the wild (individuals only survive in captivity), critically endangered (extremely high risk of becoming extinct), endangered, vulnerable, conservation dependent (these species are not severely threatened, but they rely on conservation programs to survive), near threatened (not threatened at the moment, but may be considered in the future) and least concern (no immediate threat to the survival of these species). Ecologist can also have a negative impact on the environment and its inhabitants, during their search to find more about these threatened species. They have a tendency to look at the whole ecological sphere, which decreases the value of individual creatures that are overlooked this way. They do this mostly because there is a small percentage of areas that are protected, and they have to be used into consideration when planning the preservation of some species. These actions often raise serious ethical questions. The main question here is, of course, why so many species are becoming endangered, or worst, extinct. The most widespread cause it loss of habitat, mostly because of human activity, but this also includes natural disasters. These species must then adapt to a new environment, which is never easy, or they will die. Other causes include pollution, too much exploitation, disease and climate change. Once again we can see here that humans are most responsible for the disappearance of many animals and plants. By using resources, energy and space, people make a huge influence on the wild life. There is a very logical, but disturbing statement about this: as human impact on the environment increases, the diversity of life decreases. Because it is so time consuming and costly, many people don’t bother with preservation of different animals and plants, and even question every person that does. But the fact stays, the salvation of these species is necessary for humans because they provide many good things to us, such as a source for products for human welfare, entertainment and arts, they are a sign of the health of the environment etc.