Generally, ODBC architecture is of two types single-tier and multi-tier.
This is an ODBC architecture which involves single-tier ODBC drivers. In singletier ODBC architecture, the ODBC driver receives ODBC requests/calls from the application and directly interacts with database files. It passes the SQL commands corresponding to the received calls and retrieves the results.
Example: Microsoft Access
This is an ODBC architecture which involves multiple-tier ODBC drivers. This is a common architecture and is based on client server communication.
Client: The application that makes ODBC requests, the driver and the DriverManager together considered as a client.
Server: The database and the database software (that provides DB access) together are considered as a server.
In ODBC multi-tier architecture, the application sends ODBC request/calls to the server and the server holds the ODBC calls and passes the SQL statements to the database system.
Example: Oracle, SQL server.