Screwdrivers come in to two common flavors: slotted (also called flat-head or standard), and the Phillips (X-shaped) head. A multi-bit screwdriver allows its tip to be interchanged in the shaft of the tool. The simplest type of multi-bit screwdriver will use slotted and Phillips tips, but these powerful hand tools come in sets with dozens -- or more -- of bit options, from the flat-head and Phillips basics to square-tipped, torx, sockets, hex keys, precision and insulated, among others. Some sets allow for more customized work such as those with longer bits for hard-to-reach spots, or offer trade-specific features.
Worried about losing bits? Try an auto-loading type of multi-bit screwdriver, where the bits you need are stored in and served from the shaft.