A Data Center is a location purposely designed and equipped to house servers and associated IT infrastructure. Data Centers are physically secured to prevent unauthorized access to systems and the data they contain. They should include redundant power provision with Uninterruptible Power Supply (UPS) with battery & generator-based backups to ensure continued operations in the event of a power failure in the electric supply grid.
Data Center's contain IT infrastructure that is based around standard equipment sizes and modular components that fit into racks that are designed to maximize infrastructure density while simplifying cable routing and management. The infrastructure will consist of server systems, storage systems, and networking equipment for both local and external networking. Environmental controls are also crucial to Data Centers to ensure that the IT infrastructure is kept within optimal temperatures and humidity. They should also have systems to suppress fires without damaging the IT infrastructure.
Many standards for Data Centre design and operation have been formulated. A widely used set of standards are the Uptime Institute Tier Standards. These define four tiers that range from Tier 1 (for simple and not mission critical Data Centers) up to Tier 4 that specifies multiple redundant systems to ensure continued operation in any foreseeable scenario. Each tier builds on the previous one, with Tier 2 delivering all the requirements if Tier 1 and also additional requirements.
Data Center size goes from small, serving the needs of a single organization, through to substantial industrial sized operations that provide services on the Internet via the big cloud providers such as Microsoft, Amazon, and others.