An Access database application is the overall containing unit. It contains all the tables and queries. However, an Access database application can also include forms and reports. All of these constructs exists without any need of VBA programming. An Access database application can also include VBA code.
In Microsoft Access, VBA code is organized in one of three types of containers. The term “class module” refers to a special containing unit that is used to create new objects such as forms, reports and other “things” in Access. The term “module” refers to a general containing unit that is not used to organize objects. VBA code in a “class module” is often specific to a type of objects, VBA code in a “module” is accessible throughout an entire Access database application. The term “Access class object” refers to objects already created, such as forms and reports.
Note that Access macros are separated from VBA code. Access macros, once defined, are available to the entire database application.