PIH is an acronym for "Post Inflammatory Hyperpigmentation," which refers to patches of skin that have darkened after inflammation or injury. There are several synonyms for PIH, including post-inflammatory melanoderma, post-inflammatory brown spots, and post-inflammatory dyschromia. These terms all describe the same phenomenon, which occurs when the skin produces excess melanin in response to damage or inflammation. Other related terms include melasma, freckles, and age spots, which are also caused by hyperpigmentation but have different underlying causes. Understanding the terminology for skin pigmentation disorders can help individuals communicate effectively with their healthcare providers and access appropriate treatment options.