How can you tell the difference between shielded and unshielded cat5 cable. I cannot see any information on the wire itself that would give me a clue.
The standard patch cables you buy are unshielded. Shielded has a metal "shield" around the cables inside the sheath. The plugs on shielded patch cables have a metal, or metal coated plastic outer surface. They cables may be labelled on the sheathing, S for shielded and U for unshielded, although some unshielded cables are not marked. Never mix the 2. An incomplete shielding system can induce interference, also fully shielded systems can sometimes pick up an earth loop, this can be difficult to fix, so I avoid shielded systems wherever possible.
Generally, the numbers listed on the cable itself should have a "U" or an "S" suffix.
But the easiest way to tell is to look for a little plastic strip inside the cable.
The Difference is Quality and Plastic Cord/Strap comes inside.
STP is pure copper
Check out this tutorial. It shows the difference using drawings.