A view is created from one or more base tables or from other views.
In fact, you can create hierarchies of views in which views are created from other views. This can be useful, but be aware that deleting any of the lower-level views invalidates dependencies of higher-level views in the hierarchy.
A view usually presents only a subset of the columns and rows in the base table or tables.
Moreover, some view columns do not exist in the underlying base tables. For example, it is possible to present data summaries in a view (for example, an average), which you cannot directly obtain from a base table.