The 5 Classes of Revit Elements

Classification of categories of elements followed in Revit Structure is based on their usage. 

Revit Structure uses five classes of elements:

Host

Host are elements categories that form the basic structure of a building model and include model elements such as structural walls and floors.

Components

Components are the elements that are added to host elements or act as stand-alone elements such as doors, windows, and foundations. Components are used to model building elements that are usually delivered and installed on site, such as doors, windows, furniture, and so on. Components are instances of loadable families and are hosted by other elements, which are instances of system families. For example, a door is hosted by a wall, while a freestanding component such as a desk is hosted by a floor or a level.

Annotations

Annotations are the 2D; view-specific elements that add content to the project documentation such as dimensions, tags, text notes, and so on.

Views

Views represent various orientations of a building such as plans, elevation, sections, 3d views, and so on.

Datum

Datum refers to the reference elements that assist you in creating a building model, which include grids, levels, reference planes, and so on. However they are not visible in all views, if the datum does not intersect a view’s plane (or does not intersect the plane in the correct way). Then it will not be visible in that view.

Image source: http://help.autodesk.com/view/RVT/2014

Source: Autodesk Revit Help, Global etraining

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