can't we get away without using them?

I downloaded code from http://www.vbdotnetheaven.com/Code/Jun2003/2044.asp

He has written a generic data access class which return IDBconnection and IDBAdapter interfaces (i guess???)

basically I am able to connect to the database in either of the following ways...

dim cnconnection as sqlconnection
dim idbcon as IDBConnection

cnConnection = New SqlConnection("server=vaio;Trusted_Connection=yes;database=northwind")
idbcon = New SqlConnection("server=vaio;Trusted_Connection=yes;database=northwind")

I am getting confused about IDBCOnnection...
any thoughts when it would be of help?

thanks