You may see some people knocking along a wall, listening for the tone to change when they reach a stud, but there is a more exact technology we can put to work for us. There are two ways to figure out where the studs in your walls are: Buy the latest and greatest stud finder at your local hardware store, or grab a magnet off your refrigerator (or two, depending on how powerful those magnets are).
Cutting-edge electronic sensor-style stud finders are tempting. They work by finding the edges of wood studs -- the latest technology in stud finders uses electromagnetic pulses to detect stud locations. But you don't need to use a special tool for this job. All you really need is a magnet to find a stud. Magnets can be used to find the metal drywall fasteners in wood studs (these are the screws or nails from when the drywall panels were installed) -- and they'll also find the locations of metal studs (usually found in commercial buildings rather in our homes).
While you can buy magnet-style stud finders, you can easily make one; just tie a short piece of string to a kitchen magnet and dangle it against the wall. When the magnet swings toward the wall, you've struck a stud. And once you've found the first stud, finding others based on its location is fairly easy: Studs are normally 16 inches (40.6 centimeters) on center, which means from the center of one stud to the center of an adjacent stud (but since this varies look up your local code to be sure).