Going back a few years if you were planning to build a shed for your back yard then only method available to you would be to purchase pile of lumber a few tools and get started. These days you also have the option of buying a flat pack kit from a store and simply assembling the pieces.
Flat pack sheds come partially assembled by the manufacturer. You would expect that the floor, four walls and also the roof will all be constructed, and you just have to fix them all together where you want them.
There is no doubt that flat pack sheds are certainly the easier alternative and would be my recommendation if you are pushed for time. But if I am being honest they are not my favorite approach because they generally lack individuality. For that reason if you would like something a bit special, I would recommend you build you own shed to an individual program. There are a lot to choose from, and the lumber can generally be purchased much more cheaply than a flat pack shed fees.