Definition
An IDC (Internet Data Center) is a purpose-built facility that centrally houses servers, storage and network equipment with reliable power, cooling, bandwidth and operations support — the physical foundation of internet services and cloud computing.
How it works
Racks are populated according to power budgets, backed by UPS units, precision cooling and fire suppression to keep systems running; customers can rent racks and bandwidth, or rent the servers hosted inside.
Usage
The compute behind cloud providers, video platforms, game companies and financial institutions physically sits in some IDC somewhere; high-power GPU racks in the AI era raise the demands on power and cooling, making IDC capacity a scarce resource in the race for compute.
Related and confusable terms
An IDC is a physical facility, while cloud computing is the service model that pools such facilities and sells the resources; infrastructure is the broader idea of the underlying layer, of which an IDC is the physical part.