A neoplasm is an abnormal growth of tissue characterized by excessive cell proliferation that forms a mass. These growths arise when cells lose the normal checks and balances governing their division rates, leading to uncontrolled local expansion. Neoplasms are generally classified based on their behavior: benign neoplasms are typically localized, encapsulated masses that do not invade surrounding tissues, while malignant neoplasms are invasive, capable of destroying local tissue and, crucially, the capacity to disseminate through the bloodstream or lymphatic system, a process termed metastasis. The development of a neoplasm involves complex molecular alterations that promote survival and growth, distinguishing it from normal tissue regeneration processes.