Part-level segmentation is a computer vision process that divides an object within an image or 3D model into its constituent semantic components or subparts, assigning a distinct mask to each sub-region. While standard semantic and instance segmentation methods identify and delineate entire objects as unified entities, part-level segmentation functions at a finer, hierarchical level of granularity by breaking down those entities into smaller structural elements, such as separating a human figure into a head, torso, and limbs, or a vehicle into wheels, doors, and headlights. This granular decomposition enables visual systems to analyze complex object geometries, internal spatial relationships, and localized features necessary for detailed scene understanding, robotics, and fine-grained visual recognition.