a recognition that genres are situated within discourse communities, wherein the beliefs and naming practices of members have relevance an emphasis on communicative purpose and social action an interest in generic structure (and its rationale)
Because of the potential implication of circulation disorders, darkened skin around the ankles that is not immediately explainable by simple environmental factors should be promptly called to the attention of a medical doctor for appropriate diagnosis and treatment.
1 Pregnancy hormones can cause Melasma which make dark patches of skin appear on the face.  Friction: If your thighs rub together, that skin may get darker than the rest of your body. Knees, elbows, underarms and other areas that get rubbed often are typically dark.