What is an odbc connection?

ODBC stands for Open Data Base Connectivity. It is a connection that is created to define a connection between a computer and a database stored on another system. The ODBC connection contains information needed to allow a computer user to access the information stored in a database that is not local to that computer. You need to define the type of the database application - like Microsoft SQL or Oracle or FoxPro or mySQL. Once you have defined the type of database you need to select or supply the appropriate driver for a connection (Windows already contains many of these) and then supply the name of the database file and the credentials needed to access the database.
Once the ODBC connection is created, you can tell specific programs to use that ODBC connection to access information in that database.