What is this insert?

What is this insert depends on context and what object you are referring to, as insert is something that is inserted into something else, so to identify this insert, look at where it is and what it does. This insert could be advertising insert in newspaper that is separate flyer inserted between pages for promotion. This insert could be fireplace insert metal box inserted into existing masonry fireplace to improve efficiency. This insert could be shoe insert insole placed inside shoe for arch support and comfort. This insert could be package insert card with instructions inserted into product box. This insert could be database insert statement adding data. This insert could be image insert in document. To know what this insert is, examine its material, location, and purpose, such as plastic bag insert lining trash can, or foam insert protecting product inside box. So this insert is object placed inside container or structure for protection, information, efficiency, or support, with specific name depending on application, like promotional insert, fireplace insert, or orthotic insert.