There are several types of cable shields
Solid metal tubes provide proper shielding at all frequencies, which makes them the best of all.
Unfortunately, their rigid construction severely limits cable flexibility, so they are used only in very special applications, industrial environments where EMI, chemicals, and cable crushing pose frequent threats.

Braided shields are made from very thin 40-32 AWG copper wire. The wire is woven into a braid with one flat ribbon of wires winding clockwise around the cable core and a second ribbon running counterclockwise.
The result is a stronger, more flexible cable. This type of shield best defends against lower-frequency interference (less than 10 MHz), such as that generated by AC electricity, AM radio signals, and CB radios.
Note that a shield with a signal braid cannot provide 100% protection because of gaps in the weave, especially since these gaps may expand the conductors, leaving them bent and flexed.
Braided-shield cables offer 75 - 85% coverage and provide adequate protection for most lower-frequency applications.
Cables subject to higher-frequency interference require 85 - 95% shielding, which can be achieved using double-braided shields that offer up to 99% protection.
Other type of shielding includes spiral wire shields, foil shields, and hybrid shields, all of which provide varying degrees of shielding for different kinds of applications.

Insulation and jackets
Cable insulation serves three purposes. First, it prevents contact (or short circuits) between conductors. Second, it prevents contact between conductors and the external environment. Third, it controls heat dissipation.
Insulation in most of cables consists of one or more type of plastics, which have a high resistance to the flow of electric current.
A cable jacket is the outer covering that surrounds a cable's core, shields, and insulation. Its purpose is to protect these components from mechanical damage, chemicals, moisture, and exposure to harmful environmental conditions.
Most jackets are made of extra-durable plastics that heated and forced through a die to form a continuous coating around the cable.
Such jackets are rated for use according to the ambient temperature of the environment in which they will be installed.
For example, cables designed for use in plenums, a building's air ducts, have jackets specially designed to tolerate high temperatures.