ODBC (Open Database Connectivity) is a standard API for using a DBMS (DataBase Management System). By using ODBC you can access data from a multitude of DBMSs without having to know the details of each DBMS.
How to install and configure an ODBC driver is beyond the scope of this document. Some operating systems (e.g. Mac OS X and MS Windows) ususally come with an ODBC driver preinstalled. For UNIX and UNIX-like operating systems, unixODBC (http://www.unixodbc.org) is the most common.
library(odbc) is a layer on top of ODBC. It has predicates for
opening the database, starting and executing a query, and
retrieving the results of a query.