Access is not a database server. Access is a database
engine. If you have multiple clients accessing a database through a database engine, typically multiple instantiations of the engine are manipulating the data simultaneously. This is why Access is notorious for less stability in multiuser environments, particularly across networks. It's a "too many cooks spoil the soup" scenario.
A database server, such as MySQL, PostgreSQL, MSSQL, or Oracle, runs a single database engine and uses client/server network communications to receive database manipulation requests from clients and return to clients either data, query status information, or error information.
Look at it this way: Access is like viewing an HTML file by opening the file in your browser from your local filesystem. Using a database client and server is like pointing your browser to a web server.
But having to know the database system should not be a suprise. You have to know you're using an Access database to be able to set up the ODBC connection, don't you? It's just now you're aware of more choices. (You can, by the way, run MySQL and Oracle on Win32, too. PostgreSQL, the last time I checked, is available but still a work in progress on Win32.)
The reason I pointed out that you need to know what database server your Unix environment provides is that you did not specify your Unix run environment. If you have your own server, you can use what you want. If someone else is managing the server or if you're planning on using a hosting provider, you'll probably have to use what's already have installed.
Want the best answers? Ask the best questions: TANSTAAFL!!