Stranding is an important aspect of cable construction to consider. Some cables are available in solid and stranded forms, but smaller cables are usually solid, and larger cables (usually larger than 6 AWG) tend to be stranded. When you have the option to choose it's important to understand the construction of your cable and how the differences between solid and stranded conductors could affect your application.
Solid: Solid conductors consist of just one strand of metal. They are easier to terminate than stranded conductors and are mechanically tough and inexpensive. The major disadvantage of solid conductors is their lack of flexibility.
Stranded: Stranded conductors are composed of multiple metal strands bunched together in any number of configurations. They are much more flexible than solid conductors, and the higher the strand count, the more flexible they are. While stranding can be more expensive, it is essential for any wire or cable that will need to withstand any kind of movement or flexing.