A strand is a part of the rope that is built up from individual wires. The wires in a strand can have the same form and diameter, but can also vary with regard to this. Stands can consist of one or more layers of wires, which are laid over each other. Following
strand-constructions can be distinguished:

Standard-constructions:
All wires in a standard-construction have the same diameter. As the wires in the various layers are laid in the same angle, the length of the lay differs between the layers of wires that lie on top of each other. This leads to a very small contact-surface when the wires cross. This results in more wear during the use of the rope and consequently leads to a shorter lifetime. Furthermore the rope will tend to less flexibility when longer in use.

Parallel-constructions:
The problems that are caused by the small surface of contact between the wires in standard-constructions are solved by so called parallel-constructions. To do this, wires with different diameters are used. These are laid with the same length of lay but with a differing angle. The wires in a strand that lie on top of each other then run parallel. This increases the surface of contact significantly. Thus avoiding the disadvantages as experienced with standard-constructions. Most important parallel-constructions are:

Seale (S): This construction has a same number of wires in every layer. The wires of one layer have the same diameter. The outer-wires have a bigger diameter than the inner-wires and are therefore better resistant against wear.
Warrington (W): The outer-wires in a Warrington construction have alternately bigger and smaller diameters. The number of wires in the outer-layer is twice as big as the number of wires in the inner-layer.
Filler (F): As in the Warrington construction the number of wires in the outer-layer is twice the number of wires in the inner-layer. The spaces between the two layers, however, are filled with so-called filler-wires. The filler-wires support the outer-wires and increase the metallic-surface of the rope.
Combined parallel: A construction which mostly consists of three layers of wires. The first layer is built up from wires which have the same diameter. The second layer has a number of wires twice as big as the first layer with bigger and smaller wire-diameters by turn. The number of outer-wires is the same as for the second layer and all have the same diameter. As the outer-wires are have bigger diameters the rope will be well resistant against wear, whereas the smaller diameter of the inner-wires make the rope flexible. Warrington-Seale is a good example of a combined parallel-construction.