 And I like to frame it with this question, what is required to consider something alive? Well, often sort of the first question is something that requires that there's actually a structure. So for example, a body or a cell. So we can draw some sort of structure here. And then when you have a structure, something like this, you have an inside and an outside. One of the purposes of the structure is to keep the living parts of the cell on the inside, to keep them together, to help them function. And so what are some of those functions? So they can include things like getting energy. A cell or organism needs energy to be able to grow and reproduce. This energy, if it's going to grow, it means that it's creating more biomass and that takes chemical reactions. And chemical reactions take energy to constrain. There's an increase in entropy or disorder generally in an environment, but something that's alive has this structure. So it actually has to be able to resist that entropy by expending energy. So we call this energy metabolism. So we get our energy from eating organic molecules and reacting it with oxygen to produce carbon dioxide. And we have all these enzymes within us that capture that energy for use to build our cells. And the cells are also reproducing. That reproduction requires basically a recipe for how the structure or cells can perform their metabolism. They extract that energy. So basically this recipe is what we call inheritance. And for us, that's our genetic material and how it's arranged and the chemical environment around that. So basically for something to be alive, we have to have a structure that can harvest energy to grow and reproduce. And the instructions for doing so need to be passed on. One of the key things is for this energy and metabolism and the chemical structures to keep working properly is that the inside of the cell needs to be a fairly consistent environment. The environment changes through time. And the wall or structure that separates the life from the environment helps the organism keep this consistent chemistry. And it can be things like for larger organisms things like temperature. We have a body temperature. And this consistency is called the homeostasis. So homeo is same and stasis is state. So a lot of times organisms keep a consistent chemistry within the cell. And sometimes they can't do that or they don't have enough energy for metabolism. And when these properties break down, you actually have death as part of the cell. When the requirements for life are not met, the organism dies. So we can take these ideas and make it more of a list of things that are needed. So we can annotate this with the words people normally use. Structure is one of the key aspects. The internally consistent environment is this homeostasis. The harvesting of energy is metabolism. And the reproduction and the inheritance are words that people normally use. So what we have is five properties. Structure, homeostasis, metabolism, reproduction and inheritance. And those are what makes something alive. Thanks for watching.