An air duster is essentially a tool used for cleaning, specifically removing loose dirt and dust with its pressurised blast. When looking for air dusters, you can also search for compressed air, dusting gas, or canned air, which are alternative names for the product. But despite being called "canned air," it is actually not what the name suggests. In reality, it typically comes with a nonflammable material so that you can use it near energised circuits.
You can think of an air duster as a portable air compressor line. This tool actually has many uses, allowing you to accomplish several different tasks, from simple to complex. For instance, you can use an air duster to blow cookie crumbs that you may have left on your laptop's keyboard. An air duster is also capable of clearing out vents. If you're working on a PCB assembly, you may already know that an air duster helps open up apertures in a surface mount technology (SMT) stencil.
The high spray force is what makes air dusters worthwhile. It's a misconception that these tools work the same way as a human or even a fan blowing off surface dust. For an efficient and reliable air duster, buy what you need here on The Grit.