The broadfork is a tool used to break up the compacted soil and to improve aeration of the garden soil. That means it increases the biological life of soil by helping the air and water get into the soil. This tool also allows you to unpack the soil without mixing the surface soil and the deeper soil. It also is known as U-fork or grelinette.
Basically it is an essential tool for gardening. But why you spend money if you can build it at home.
Here I explained in detail with illustration how to make a broadfork.