Many ethernet cables consist of what is known as a 'Twisted Pair' which is a type of cabling in which two conductors of a single circuit are twisted together for the purposes of improving electromagnetic compatibility and to reduce electromagnetic interference (EMI). So when looking at the names used for certain ethernet cables, it's easy to work out that the 'TP' stands for 'Twisted Pair'. So, that leaves us to work out what the 'U', the 'F' and the 'S' stand for.
Some environments are prone to greater amounts of EMI, so there are cables designed to provide even more protection against interference. This protection is called shielding.
When used in a home or small office environment that doesn't have a whole lot of equipment that will cause EMI, a normal twisted pair ethernet cable will usually perform just fine. This cable is known as an "unshielded twisted pair" or UTP for short. This cable is much less expensive to buy as it comes without any extra internal shielding and due to this fact, it is thinner and more flexible to work with, therefore easier to install.
We now consider the shielded ethernet cables – FTP and STP. The terms can be a bit confusing as they are often used interchangeably and each has extra components inside the cable in order to protect signals from interference. However, there is a difference between them:
FTP specifically uses a foil 'F' shield wrapped around the outside of the twisted pair package, offering an additional layer of protection with shielding wrapped around the individual twisted wires. This protects against EMI and crosstalk and is common in 10GBaseT applications.
S/UTP and F/UTP – Shielded/Screened 'S' or Foiled Unshielded Twisted Pair Cable offers an overall foil or braid screen covering the four pairs of unshielded twisted pairs.
S/FTP – Shielded and Foiled Twisted Pair – is 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.