There are many potential causes of hair loss, including genetics, hormones, thyroid disease, diabetes, physical illness, autoimmune diseases, cancer treatments, surgery, Alzheimer’s disease, prescription or recreational drugs, extreme dieting, eating disorders, and stress. Hair loss can be categorized as hair shedding or hair shredding, with hair shedding being the complete loss of hair from the root, while hair shredding involves hair breaking off at the root or somewhere along the hair shaft. Male-pattern hair loss usually begins above the temples and at the vertex of the scalp, while female-pattern hair loss more commonly causes diffuse thinning without a hairline recession. Hair loss can occur in people of all ages and genders, and some forms of hair loss may be temporary or reversible with proper treatment.