Contained within MS Access is a complete multi-tiered database tool set.
The data tier contains tables, relationships & indexes.
The user interface contains forms & menus.
Business rules are contained in the VBA (Visual Basic for Applications) layer.
Reporting is handled by report objects.
MS Access is a mature product with many versions. At its heart is DAO (Data Access Objects) which to date has not been successfully replaced by an ADO version. (The UIF is simply too tightly bound to DAO) In brief, MS Access is rigorous & complex, with many caveats. In the past 10+ years, I have a long list of "interesting cases." I will start documenting them here.