Infra- means below, and sometimes these elements are literally below the ground, like water and natural gas supply systems. In modern environments, infrastructure is thought to be any facility we expect but don't think about because it works for us in the background, unnoticed — below our radar. The global information infrastructure being developed for communications and internet involves satellites in space — not underground at all, but we rarely think about how that last Tweet got to us so quickly.
Infrastructure is often misspelled as "infastructure." Knowing that some words begin with infra- helps define them. The word infrared describes eletromagnetic rays with wavelengths under the color red; compare this with ultraviolet waves, that are beyond (ultra-) the violet color.
All countries have infrastructure in some form, which can include these systems:
- Roads, tunnels, and bridges, including the Interstate Highway System
- Mass-transit systems (e.g., trains and rails)
- Airport runways and control towers
- Telephone lines and cellphone towers
- Dams and reservoirs
- Hurricane barriers
- Levees and pumping stations
- Waterways, canals, and ports
- Electrical power lines and connections (i.e., the national power grid)
- Fire stations and equipment
- Hospitals, clinics, and emergency response systems
- Schools
- Law enforcement and prisons
- Sanitation and waste removal facilities — solid waste, wastewater, and hazardous waste
- Post offices and mail delivery
- Public parks and other types of green infrastructure