Display form at start up

There are two commonly used options:

1)There is an option to select the desired start up form:

Access 2000/2002/2003 -On the Menu -  Tools Startup... > Display Form/Page

Access 2007 - Office Button (upper left corner) > Access options (lower right) >
                         Current database >  Display Form
Access 2010 - File > Options > > Current database >  Display Form

2) use a macro named AutoExec

Action - OpenForm