What does "insert" mean in a picture?

What does insert mean in a picture refers to small picture, photo, diagram, or image that is set inside larger main picture to provide additional detail, context, or close up view, also called inset picture or picture in picture. In picture, insert means small image placed within larger image, such as inset map showing enlarged area of main map, or insert photo of person inside main landscape photo, or close up insert showing detail of object in main picture. In photography and graphic design, picture insert is technique where small image overlays or is placed inside larger image to highlight detail. In film, insert shot is close up shot of object inserted into scene. So insert in picture means small secondary image embedded inside primary image to show detail, additional information, or highlight, similar to inset, often bordered and positioned in corner of main picture, providing extra visual information without replacing main picture.