Understanding domain and range is really important in many areas of life. Here are a few examples:

1. Economics: When we look at how profit works, we can use a formula like $P(x)$, where $x$ is the number of products sold. In this case, we can say that $x$ has to be zero or more (so $x \geq 0$). You can't sell a negative number of products!

2. Engineering: When engineers study materials, they use graphs that show how much stress (force) a material can handle. These graphs help us know the limits of materials. They often show the relationship using $E = \frac{\sigma}{\epsilon}$, which helps us understand how much a material can stretch or compress.

3. Environmental Science: Scientists study populations using models like $P(t)$, where $t$ is time. Here, the time must be zero or more (so $t \geq 0$). The range tells us the possible sizes of the population. For example, it could show that a population will not be more than 1000 (like $P(t) \leq 1000$).

These examples show just how useful understanding domain and range is in different fields.