What is twisted pair?

Twisted pair is a type of cable made of pairs of copper wires twisted together, used to transmit data in computer networks.

Put simply: twisted pair is an Ethernet cable in which the wires are deliberately twisted to reduce interference.

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#Why are the wires twisted?

Twisting is not an accident, it is a way of fighting interference.

When the wires are twisted:

• external interference affects both wires equally
• on reception, this interference cancels out
• the signal becomes more stable

Thanks to this, data is transmitted more reliably and over a longer distance.

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#How twisted pair is built

The cable usually contains:

• 4 pairs of wires (8 conductors in total)
• each pair is twisted with a different pitch
• copper conductors inside
• an outer insulation layer

A different twist pitch is needed so that:

• the pairs interfere with each other less

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#Types of twisted pair

#1. UTP (Unshielded Twisted Pair)

• no shielding
• the most common
• cheaper

Used:

• in offices
• at home
• in ordinary Ethernet networks

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#2. STP / FTP (shielded twisted pair)

• has a metal shield
• better protected from interference
• more expensive

Used:

• near sources of interference
• in manufacturing
• in server rooms

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#Twisted pair categories (briefly)

The category affects speed and frequency:

• Cat5e: up to 1 Gbps
• Cat6: up to 10 Gbps (over short distances)
• Cat6a: up to 10 Gbps (up to 100 m)

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#The role of twisted pair at the physical layer

The physical layer:

• uses twisted pair as the transmission medium
• accounts for its length, interference, and category
• determines the maximum speed and distance

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#Simple analogy

Two people carrying a heavy object:

• if one stumbles, the other compensates The same happens with the wires in a twisted pair - interference gets "canceled out".

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#Briefly, for the interview

Twisted pair is a cable made of twisted pairs of copper wires, used to transmit data and reduce the effect of electromagnetic interference.