Everyone has tons of stuff. And everyone has stuff that they don't need all the time. Your seasonal items - Christmas decorations, for example - can be stored away in plastic storage totes. They cost about $5 on sale for an 18 gallon tote. But once you have your things stored away, where are you going to keep them? You can stack them in your attic, garage, or shed, but a stack of totes 5 high is not very stable, and Murphy's Law says that the tote you need is going to be at the bottom of that stack.
So, off to Lowe's or Home Depot you go, and when you find the right Storage Shelves, you look at the price: It's going to cost you $80+ for a set of 48"W x 24"D x 72"H shelves that will hold ten 18 gallon totes! And if you've been diligent and read the reviews, you find a problem with these shelves - the shelving material is particle board, and the shelves sag in the center if you put a load on them. Not to mention, although they're "commercially built" shelving units, they come in a box and you still have to build them.
Let me save you all those steps and a bundle of money, and show you how to build a simple set of shelves for under $25, using simple tools in about an hour.