2 very common types of metal roofing are a Galvalume 5V and Galvalume Standing Seam.
5V earns its name from having 5 V's on each panel. The V dimension serves as a way for the panels to interlock and be securely fstened by the stainless steel fasteners. These fasteners are equipped with rubber washers to create a water tight seal. They are secured throiugh the overlapping panels into the roof deck every 12 inches. This roofing system offers a longer life duration than a typical asphalt shingle roof, while also adding that modern or futuristic look.
The other common type of metal roof is known as a standing seam metal roofing system. These type of panels actually interlock panel to panel. No screws, rather an interlocking system. They are secured at the top (under the ridge cap) and at the bottom (tucked under lip of drip edge). Many believe this look is more aesthetic and less likely to leak because there are no screws used in the securing process.
Either way, metal is becoming much more popular and viewed as the new age roofing system!