A drill-driver, sometimes simply called a "drill," is a versatile power tool that combines the functions of a drill and a screwdriver. This tool allows you to drill holes in materials and drive screws. Here are the key characteristics and functions of drill-drivers:

1. Motor and Power Source: Drill-drivers can be electric (corded) or cordless. They operate either by connecting to an electrical outlet or by using a built-in rechargeable battery. Cordless models provide greater mobility as they do not require a constant power source.

2. Adjustable Speed and Torque: Many drill-drivers have speed and torque settings that can be adjusted depending on the task and the type of material.

3. Variety of Attachments: They typically come with various attachments and bits, allowing them to be used for drilling holes, driving screws, and more.

4. Bi-directional Operation: Drill-drivers can work in both forward mode for drilling and screwdriving and in reverse mode for unscrewing.

5. Applications: Drill-drivers are used for a wide range of tasks, including woodworking, construction, repairs, metalworking, and more. They are indispensable for drilling holes and driving screws accurately and efficiently.

Drill-drivers are versatile tools that save time and effort in various tasks related to material processing and assembly.