Spreading and duplicating.
WHAT LOAD BALANCING IS
Distributing requests across several servers.
WHY
Capacity beyond one machine Continuity if one fails
WHAT IT REQUIRES
Servers able to serve the same content Shared or synchronised data Session handling that works across servers
THAT LAST POINT
Sessions held on one server break when a visitor is sent to another.
WHAT REDUNDANCY MEANS
More than one of something, so a failure does not stop service.
WHERE IT APPLIES
Servers Connections Power Data
WHEN A SMALL BUSINESS NEEDS THIS
Rarely.
Good hosting with backups usually suffices.
WHAT TO DO INSTEAD
Ensure you can restore quickly Ensure backups exist off the server
WHAT REDUNDANCY COSTS
Complexity, which itself causes failures.
WHAT TO ASK BEFORE PURSUING IT
What outage duration you can actually tolerate.
Most small businesses can tolerate more than they assume.