Decomposition of time series

Let's say you have a big piece of cake that you want to share with your friends, but you want to know how much chocolate is in it and how much vanilla is in it. You can use a knife to cut the cake into slices and then count how many have chocolate and how many have vanilla.

Well, the same thing can happen with time! Sometimes we want to know how much of something happened at different times, like how much it rained each month or how much money a store made in different quarters. But just like with the cake, we need to break time into smaller parts and look at each one.

This is where "decomposition" comes in. It means breaking down something big into smaller parts. With time, we can break it down into smaller parts called "seasons," like different parts of the year, or "trends," like if something is going up or down over time. We can use math to figure out how much of each season or trend there is in the whole time period.

Once we know the different parts, we can add them up to get the whole thing again. It's like putting the cake back together after cutting it into slices. Now we know how much chocolate and vanilla was in the cake, and we know how much of something happened in different parts of time. Pretty cool, huh?