The level of detail calculations (LOD) enable you to tell Tableau Public at exactly which dimensional level you would like to aggregate without having to place that dimension on the visualization. Additionally, you can include or exclude dimensions in the calculations and create calculations that include all the underlying data.
The following are the three types of LOD calculations:
LOD has a big caveat. While you can perform table calculations on them and create aggregations and functions within them, you cannot include table calculations in them.