A species classified as endangered is in serious danger of extinction in the near future. As of May 2014, there were nearly 17,000 endangered species in the world, according to Endangered Species International.
The most common reason species become endangered is due to habitat loss. Logging, mining, cattle ranching and oil development are just a few of the activities that contribute to this.
In some cases, a species becomes endangered because other plants or animals have been introduced to their ecosystems. These additional species may compete for resources or carry diseases that kill native species.
Population growth and pollution also put plants and animals at risk. When the population of an area expands, there is a greater need for housing and food. Humans may clear natural areas to build new homes or start eating more of the plants in an area. Pollution damages the ozone layer, contributing to global warming and putting plants and animals at risk.