This document discusses different element types in Building Information Modeling (BIM) applications like Revit. There are three main types of elements: model elements that represent actual building geometry like walls and doors, datum elements that define the context like levels and grids, and view-specific elements like dimensions and tags that are only visible in certain views. Model elements are further broken down into host elements that are built on site, like walls, and model components like windows and beams. The document provides examples of element types for Revit Architecture, Structure, and Mechanical, Electrical, and Plumbing applications.