• Using the right screw ensures a good bond.screw image by Henryk Olszewski from Fotolia.com
  
  There are literally thousands of different sizes of screws, but just a few thread types. The shank of a screw may either be tapered or straight, depending on what it is designed to be used for. Screws give a far more stable joint between two materials than nails do, and the type or name of screw usually depicts the material on which it is to be used.
  
  

Wood Screws

• Wood screws.wood screws image by Darko Draskovic from Fotolia.com
  
  You can find wood screws at all hardware retail outlets. The full range of sizes starts at 0, which corresponds to a shaft diameter of 0.06 inch, and goes up to 24, or 0.372 inch. A wood screw has a tapered shaft with a short untapered section immediately below the head. It usually has a deep thread to enable it to get a good grip onto the wood.
  
  

Sheet Metal or Self -Tapping Screws

• Self-tapping screws.screws image by Eldin Muratovic from Fotolia.com
  
  Sheet metal or self-tapping screws come in the same sizes as wood screws, namely 0 through 24. They have tapered shafts with threads extending all the way to the heads. These screws have a sharp thread that enables them to cut their own way into the substrate. This is usually metal but can be plastic or other similar materials.
  
  

Machine Screws

• Machine screws.slotted machine screws image by Tom Oliveira from Fotolia.com
  
  The distinguishing feature of machine screws is that they have a straight shaft and a much finer thread than wood screws or self-tapping screws. They are designed to be screwed into a bolt or into a pre-tapped hole, usually in metal. Machine screws can be found in the standard sizes of 0 to 24, but the most common are sizes 6 (0.138 inch), 8 (0.164 inch) and 10 (0.190 inch) diameter.
  
  

Concrete or Masonry Screws

• Masonry screw with anchor.bolt image by Grebenshchikov from Fotolia.com
  
  Concrete screws, sometimes known as masonry screws, are self-tapping screws that are designed to be screwed into pre-drilled pilot holes in concrete. They have a shaft diameter of at least 0.325 inch and each has a hexagonal head so it can be tightened with a wrench. They are used for attaching machinery or similar items to a concrete base. Some concrete screws come with an attached anchor that expands as the screw is tightened, thus giving a stronger bond.