A power screwdriver is a tool that makes use of a small motor and an interchangable bit system. The particular model I am describing is a Black & Decker Pivot Driver with an adjustable neck. They are typically run on batteries, some internal, some external like the versapak, and most are rechargeable. Some of the finer models have both forward and reverse functions. Usually the bit is interchangeable, but the most common is the phillips head and the standard head. Common uses include household projects and more imporantly, small electronics repair.