Final answer:
The four common hair patterns when designing a style are straight, wavy, curly, and extremely curly, which are considerations for the hair's behavior during styling.
Step-by-step explanation:
The four common directional patterns, or waves, found in all hair that must be considered when designing a style are straight, wavy, curly, and extremely curly. These patterns are important for determining how a hairstyle will look on an individual, as each pattern behaves differently in terms of styling and maintenance. When hair gets wet, the water molecules can temporarily disrupt hydrogen bonds in the keratin strands, allowing the hair to adopt a new shape during the drying process. However, the original wave pattern of the hair returns once it's fully dry unless a permanent chemical treatment is applied to alter the pattern.