GRADE 2: Low carbon hex head steel bolt.  Ideally suited for holding wood pieces together or general hardware use where higher strength is not required.  There is no grade marking on the head of Grade 2 fasteners.	GRADE 5: Through hardened hex steel bolt.  Grade 5 fasteners are made of medium-carbon steel.  Quenched and tempered for the additional strength necessary for most automotive uses and other applications where strength is a moderate concern.  Grade marking  is 3 equally spaced lines coming out from center of head.	GRADE 8: Through hardened hex steel bolt.  Grade 8 fasteners are manufactured of medium-carbon alloy for the most demanding applications.  Quenched and tempered to superior strength and hardness qualities.  Grade marking is 6 equally spaced lines coming out from center of head.
STAINLESS:  Hex head bolt; typically 18-8 (300 series stainless) to prevent corrosion.  Has a smooth body with threading on the end and a head marking of 2 lines.  Thread length is generally twice the diameter of the shank plus 1/4" on lengths up to 6" and twice the diameter plus 1/2" on lengths over 6".  Normally installed with 2 flat washers and a hex nut.	HEX TAP BOLT: Fully threaded used to fasten two or more parts together to form an assembly either because it cannot be manufactured as a single part or to allow for maintenance and repair disassembly.  No washer face under head.	HEX CAP SCREW:  A hex bolt whose thread is determined by: 2x the diameter + ¼”; small washer face under the head.
CARRIAGE BOLT:  Small washer face under round head with a square neck to prevent spinning.  Suitable where strength and corrosion resistance are primary considerations.  Steel is zinc plated for moderate protection against rust.	HEX LAG BOLT:  Come in longer lengths than wood screws and are easy to tighten with a wrench.  Zinc plating helps to prevent corrosion.  Can be driven with simple wrenches and require minimal clearance above the fastener because they can be driven or loosened from the side.