UTP cable (Unshielded Twisted Pair)
Twisted pair cable is the most used, it does not possess any additional protection to the PVC coated and it has 100 Ohm impedance. The connector most commonly used in this type of cable is the RJ45, similar to the RJ11 used in phones (but a little large), but they can also be used other (RJ11, DB25, DB11, among others), depending on the network adapter. It is undoubtedly that so far has been better accepted, accessibility cost and easy installation. But at high speeds it can be vulnerable to electromagnetic interference of the environment.
STP cable (Shielded Twisted Pair)
In this case, each pair is covered by a conductive mesh which acts as a screen against interferences and electrical noise. Its impedance is 150 Ohm. The level of protection of the STP to external shocks is greater than the one offered by UTP. However it is more expensive and requires more setup time. The screen of the STP to make it more effective requires a configuration of interconnection with Earth (with continuity to the terminal), with the STP is commonly used connectors RJ49. It is usually used in data processing facilities for its capacity and its good properties against electromagnetic radiation, but the downside is that it is a sturdy, expensive and difficult to install cable.
F/UTP cable (Foiled Shied with uUnscreened Twisted Pair)
In this type of cable as in the UTP, peers are not shielded, but if it has a global screen to improve your level of protection against external interference. Its typical impedance is 120 ohm and its transmission properties are more similar to the UTP. You can also use the same RJ45 connectors. It has a mid-priced between UTP and STP.
S/FTP cable (Shielded and Foiled Twisted Pair)
A combination of the two above, with foil shielding around the individual twisted wires and an overall screen which can sometimes be a flexible braid.This provides the maximum level of protection from interference and is found in the highest performance cables.
