 In this video, we are going to look at a few key words that you will come across throughout ecology. Let's start by looking at the whole thing, the ecosystem. An ecosystem is made up of all the communities that live in it, every single organism from big to small, and lots of environmental factors like sunlight, shade, the woodland, streams and other things. An ecosystem is defined as a biological community of interacting organisms and their physical environment. A habitat is an area or environment in which an organism naturally lives, so the woodland in this example. It describes the geographical area occupied by the ecosystem, whereas the ecosystem is the interactions between everything living within it as well as the non-living factors. Populations are all members of the same species in the habitat at one time. While populations describe just one species, a community is all the organisms in multiple species that coexist in the habitat at one time. So the community is the foxes, rabbits, insects, plants, fungi and everything else living in the woodland. A niche describes the role of a species within an ecosystem. So a bee's role is to pollinate the flowers. The rabbit's role, or niche, is to be a small grazing prey animal with a very high reproduction rate, which supports many predators in the ecosystem. A species is a group of potentially interbreeding individuals, which do not normally reproduce with other species to produce viable fertile offspring. So here in our woodland, we have foxes and rabbits that are clearly different species. But we may also have a few different species of butterfly. Maybe one lives on the outside of the woods and likes light, while another lives deeper in the wood. And because they prefer different areas of the wood, they don't interbreed. We will look at what it really means to be a species in another video, and we'll also revisit all the words throughout ecology. For now, you just need to know the difference between a habitat and ecosystem, a population and a community, and how species have a niche within the ecosystem.