A bit is a tool. It is a short, interchangeable screwdriver blade without a handle that fits into a specific screw head profile. Most holders are hexagonal in shape. This allows most standardised bit holders to be inserted. Most bits are held in their fixture by a magnet. A bit holder lies between the bit and the drive (cordless screwdriver or screwdriver).
The bit holder can be directly connected to the drive. This is the case with a handle or cordless screwdriver.
Alternatively, an adapter can also be used. This can be connected to a screwdriver handle or an angled handle, a ratchet or a torque spanner, or to a screwdriver with a universal outlet, such as a drill chuck or square drive. This is often the case with cordless screwdrivers, rotary screwdrivers, impulse screwdrivers or ratchet screwdrivers.