 So it's important to understand what ecosystems are. Ecosystems, it's a word we use in science to describe the living creatures and the non-living materials. So we talk about plants and animals and living, but then the air and water is non-living. But the living creatures and the air and water all interact at the level of a system. And they do that on big scales. So often when we talk about an ecosystem, we're talking about a whole landscape, a whole valley or even more than that with animals in trees and the trees with their roots in the soil and the water going through the soil and the trees are absorbing gases from the atmosphere and releasing them and so on. So it's a word that tries to encapsulate the way those things interact at big scales. Why are they important? On one level that almost seems like a silly question because they're so important. We are part of an ecosystem. That's probably the best way to think about it. You can't have humans without having an ecosystem. Even if we end up sending humans out to live on other planets, they're going to be supported by things that were made on Earth that are products of the ecosystem of Earth. So you kind of can't... Well, so far we haven't had life without ecosystems. We're just bound to them. The fact that we breathe in and out constantly and those gases are being produced by the plants and animals in the landscape or at least being shaped and influenced by plants and animals in the landscape means that every second you're connected to an ecosystem. So if you've grown up in a modern technological society, it's easy to sort of slowly forget the extent to which you're connected to nature. And so as that sort of phenomenon developed in, especially in Western societies, so developed this idea of ecosystem services. And ecosystem services was really a framework for helping people to understand and reflect on the ways that actually, even though they might think they're separating from nature, they're not. We rely on ecosystems to provide all of these things that we consume, food and water, and to provide the environment in which we can survive. So ecosystem services or the ecosystem services framework is a way of accounting for all the ways in which nature is supporting humans on a day-to-day basis. So it's deliberately human-centric. It's kind of like saying, what has nature done for us? And so it forces you to reflect on those connections and then start to think about how do we make better decisions about how to manage our environments to make sure that they can continue to support us humans. On one level, maybe the ecosystem services framework sounds kind of obvious and simple.