Backbone
From Unofficial BOINC Wiki
[edit] General
A part of a network or other system that supports the rest of the system by carrying the largest load. In the case of the BOINC Client Software the backbone is another way to describe the function of the BOINC Client Software because is supports all of the rest of the Science Applications. The other part of interest is hidden way behind the scenes as part of the Internet because there is a backbone structure of high-speed data links that connect all of the Internet together.
