Aβ, or amyloid-beta, is a peptide that is primarily associated with Alzheimer's disease. It is formed from the cleavage of a larger protein called amyloid precursor protein (APP). Aβ can aggregate to form plaques in the brain, which are believed to disrupt cell function and contribute to neurodegeneration. The accumulation of Aβ plaques is one of the hallmark features of Alzheimer's disease and is used as a key indicator in diagnosing the condition. Research continues to explore the role of Aβ in the disease process, as well as potential therapeutic strategies to target its formation and aggregation.