The strand is the simplest wire construction, it consists of several wires helically wound whith one or more overlapping layers. The number of wires that make up a strand can vary greatly. The strands are generally used as a part of more complex cables but also on their own.
Characteristics such as resistance to fatigue and abrasion are directly determined by the construction. In strands with two or more layers the inner layers support the outer layers, so that the wires can slide and adjust freely as the rope flexes.
In the case in which the different layers are wound in the same direction, strands with parallel wires are defined and strands with crossed wires when the direction of rotation of the successive layers is different.
The simplest strand is the 7-wire strand. Parallel strands made up of wires of the same diameter can cause slippage that causes wear. For this reason, constructions that use a greater number of wires of different diameters have been developed. These are typically the Filler, Seale, Warrington and Warrington-Seale constructions.