Which type of tumor is characterized as not cancerous and often encased in a capsule?

Benign tumors are non-cancerous growths that typically grow slowly and are usually encased in a capsule. This encapsulation means they are well-defined and easier to distinguish from surrounding tissues, which often allows for complete surgical removal without significantly affecting the surrounding structures. Unlike malignant tumors, which invade nearby tissues and can spread to other parts of the body, benign tumors do not metastasize. Therefore, they pose a lower risk to the overall health of an individual, although they can still cause problems depending on their size or location, especially if they press on surrounding organs or tissues.

Neoplasms is a broader term that encompasses both benign and malignant tumors, while metastases specifically refer to the spread of malignant cells to distant sites in the body. Malignant tumors are characterized by uncontrolled growth and the ability to invade neighboring tissues, leading to significant health risks and complications. Thus, the defining characteristics of benign tumors make them distinctly different from other types mentioned in the question.