A Structured Data Cabling system is a complete system of cabling and associated hardware, which provides a comprehensive telecommunications infrastructure.  This infrastructure serves a wide range of uses, such as to provide telephone service or transmit data through a computer network.  With a correctly installed system, current and future requirements can be met, and hardware that is added in the future will be supported. Structured cabling design and installation is governed by a set of standards that specify wiring data centers, offices, and apartment buildings for data or voice communications using various kinds of cable, most commonly category 5e (Cat 5e), category 6 (Cat 6), and fiber optic cabling and modular connectors.

Structured cabling consists of six subsystems:
Entrance facilities is the point where the telephone company network ends and connects with the on-premises wiring belonging to the customer.
Equipment rooms house equipment and wiring consolidation points that serve the users inside the building or campus.
Backbone cabling is the inter-building and intra-building cable connections in structured cabling between entrance facilities, equipment rooms and telecommunications closets. Backbone cabling consists of the transmission media, main and intermediate cross-connects and terminations at these locations. This system is mostly used in data centers. 
Horizontal cabling wiring can be standard inside wiring (IW) or plenum cabling and connects telecommunications rooms to individual outlets or work areas on the floor, usually through the wire ways, conduits or ceiling spaces of each floor. A horizontal cross-connect is where the horizontal cabling connects to a patch panel or punch up block, which is connected by backbone cabling to the main distribution facility.
Telecommunications rooms or telecommunications enclosure connects between the backbone cabling and horizontal cabling.
Work-area components connect end-user equipment to outlets of the horizontal cabling system.
The methods we use to complete and maintain cabling installations are relatively standard. The standardization of these installations is necessary because of the need to ensure acceptable system performance from increasingly complex arrangements.
The benefits of these standards include:
Consistency of design and installation;
Conformance to physical and transmission line requirements;
A basis for examining a proposed system expansion and other changes; and
Uniform documentation.