 When we talk about concentration in solutions, we're primarily, or at least if not primarily, a good bit of the time, we're talking about molarity. And molarity is defined with a capital M, or it symbols a capital M. It is defined as moles of solute per liter of solution, moles of solute per liter of solution. Now, a lot of people are mixed on this, but I love these triangles because the triangles are so useful in teaching this concept. They work this way. If you cover up molarity, you can see that molarity is defined by moles over liters. If you wanted to calculate the number of moles that are in a solution, if you cover up moles, essentially what it's telling you to do is to multiply molarity times liters. And if we were interested in the volume, you would cover up volume and you would determine that molarity divided, I'm sorry, moles divided by molarity would give you your volume. Three reactions or three mathematical manipulations you can do using this. For people who aren't good with mathematics, good with algebra, all you need is that molarity is equal to moles over liters and you can manipulate that to solve for whatever you need. So that's certainly an important thing.