Screws.

Screws

These are three different types of screw.

Countersunk: First you drill a pilot hole into the wood. Then you can widen out the top by using a countersink drill bit. The head is flat on the top.

WHIT CSK Socket Set Screw
WHIT CSK Socket Set Screw

 

Raised head: Has a slightly domed head, raised above the surface.

Metric CSK Raised Slotted Machine Screw
Metric CSK Raised Slotted Machine Screw

 

Round head: Domed head above the surface, broader than underneath

Woodscrew Round Slotted
Woodscrew Round Slotted