This bed is probably the most important aspect of your truck, and should have been the reason you purchased a truck instead of an SUV. It is not only an important aspect, but an important investment, therefore you should protect it. Here are a few options:
First is the classic drop-in bed liner. This is a plastic compound that has been form fitted to your specific truck and is “dropped in” to the bed. It is then fastened to the bed by a number of bolts.
More popular nowadays is the spray-on bed liner. This involves spraying a compound to the bed of your truck. When it dries, it forms a hard, protective layer around the bed.
You also have the more economical bed mat. This is just a basic sheet of plastic that goes into the floor of the bed that is cut to fit around the wheel wells. They offer minimal protection to the floor of the bed and no protection to the walls.
I chose a drop-in bed liner for my truck. I have one reason: easy to move payload. This may seem like a bad thing as opposed to spray-on bed liners that prevent your payload from sliding, but think about it. I want it to be easy for me to move the load in my bed, whether it is putting it in or taking it out. If I do not want my load to move, I use the ratchet straps that I keep in my toolbox to tie the load down. It was the ease of loading that made me go with the drop-in bed liner.