One of the most useful features of a Microsoft Access database is the ability to split the database into two files. The first file, which is commonly called the back-end or data file, holds the data (the tables). The second file, which is commonly referred to as the front-end or shell file, contains the user interface (queries, forms, reports, macros, and modules).
Splitting the database has two main benefits. First it allows a company to keep the data on a central file server and the interface on multiple individual workstations. That way if a user has an unfortunate problem that corrupts the database, the good news is only their copy of the shell becomes corrupted. Other users are able to continue using the database without a problem.
The second benefit relates is a developer can enhance an offline copy of the shell while others continue to use the live database.