Self-tapping screws, also called sheet metal screws, are very versatile. They can be used to securely fasten metals together, including aluminum. They can also be used to efficiently fasten metal to other materials, such as wood or plastic, by creating a much stronger bond than a regular nail.
Aluminum has many characteristics that make it easy to work with. It's lightweight and easy to shape. However, aluminum is also known to vibrate, and when used as building material for boats, for example, this can be a problem when the engines cause the frame of the boat to vibrate. Regular screws and nails have a tendency to come loose under vibrations, and so they are not effective fasteners for aluminum. Trilobular stainless steel self-tapping screws, on the other hand, are ideal. Self-tapping screws are like drill bits; they have a sharp tip like a cutting blade and a thread that goes all the way down the length of the screw. They are designed to keep thin metal from denting.
To use self-tapping screws, place the screw directly on the aluminum sheet. Stabilize the screw so it doesn't tilt as it goes in and twist the screw into the metal. Let it turn until it goes all the way through, as the threads and the sharp point make their own hole. Be careful not to over-tighten the screw since the metal can be damaged or the screw can break.
The advantage of using self-tapping screws for aluminum is that they don't need pre-drilling and are easily removed without damaging the metal. They can also be reused in the same material.