Backbone

Backbone is a high-speed line or series of connections that forms a major pathway within a network.

The Internet backbone refers to the main "trunk" connections of the Internet. It is made up of a large collection of interconnected commercial, government, academic and other high-capacity data routes and core routers that carry data across the countries, continents and oceans of the world.

The term is also relative as a backbone in a small network will likely be much smaller than many non-backbone lines in a large network. In general, the better the backbone of the hosting company, the better the availability of the web sites that run on their computers.