Although Im not positive of what you are looking for, DataAdapters are basically the bridge between a data source (a database like SQL Server or Oracle) and a dataset used in your program (holds a set of data from the database.....like a temporary table). Information is then manipulated however you want between the two using the DataAdapter.
There are as many types as there are .Net providers. Default VS.Net will come with 2 or 3 (SqlClient, OLEDB, ODBC.Net). MS also makes an Oracle provider I believe. IBM makes an iSeries provider. Other vendors make their own.