
The infrastructure of a municipality includes the physical and built form of its housing, public facilities, transportation, utilities and other support systems for its people. An infrastructure can also be viewed as any facility that provides support to the economy of a region or country.
One definition is “the framework for an economy in terms of what it produces”. An infrastructure includes everything from factories to power stations. A city’s water distribution system is an example of one part of an infrastructure in action; highways, railways lines and airports are another.
In some cases national infrastructures may include longer term investments like dams, bridges and mass transit systems like trains or subways which may take decades or centuries to build depending on the size & location.
Infrastructure may be owned and managed by government or by private companies, such as sole public utility or railway companies.

Framework for an economy – the fundamentals of infrastructure include a well-developed transportation system, an effective electric power grid, a healthy water supply system and other basics that make the economy work.
the fundamentals of infrastructure include a well-developed transportation system, an effective electric power grid, a healthy water supply system and other basics that make the economy work. Public facilities – these are necessary to support all economic activity in all our communities including roads, highways, airports & seaports, utilities and public spaces (parks & green spaces).
these are necessary to support all economic activity in all our communities including roads, highways, airports & seaports, utilities and public spaces (parks & green spaces). Housing – Maintaining a healthy residential housing market is vital for our ongoing success.
Maintaining a healthy residential housing market is vital for our ongoing success. Transportation investments in transportation infrastructure have the potential to significantly reduce operating costs and country risk.
From http://www.investopedia.com/terms/i/infrastructurefinancing.asp:
Infrastructure financing involves getting money to either build new infrastructure projects or renovate existing ones, such as building new roads or maintaining bridges. In many cases, the money comes from multiple sources.

The three main sources of financing for infrastructure projects are:
-local government revenues;
-investors through private placements; and
-international institutions like the World Bank.
Investors tend to be more interested in long-term assets they can hold onto for a long time, and more interested in projects that have a revenue stream attached to them, such as tolls on a bridge. Because international institutions lend at lower rates than private investors, often times those loans are used by local governments to help subsidize private investments or even pay them off.
It is important to note that a country’s infrastructure does not necessarily have to be owned by the government. It can be owned by private companies. In fact, some of the most widely used and profitable ones are privately owned, such as utilities and toll roads.
From http://www.devproforum.com/content/1074-how-do-you-define-infrastructure:The Essential Definition of Infrastructure
When asked to define infrastructure, most people can come up with some very basic ideas about it, yet are unable to accurately articulate them.
But, among the general population, there are multiple definitions, each of which is similarly vague and perhaps even contradictory. In fact, the technical experts that define infrastructure could in some cases be considered as having a definition more commensurate with that of the average public.
The following two examples of this phenomenon illustrate very well how both definitions can be equally dissatisfying to all sides:
One healthcare administrator can define “infrastructure” as “a support system for an organization”. To a CPA, this may sound like it is referring solely to financials. To the end user or physician this looks like a very basic description; yet to someone else it might mean something entirely different.
One may view housing as “infrastructure” and feel compelled to include it among the basic definitions, however not all housing is the same. Some poor housing conditions such as slums or elevated squalor are clearly undesirable. But even in lower income areas there are some very decent examples of construction, with a comfortable level of interior finishes, that would be considered “adequate” by those who are familiar with the American standard of “good housing”.

Thus we find ourselves at a cross roads. We have two fairly reasonable definitions for infrastructure in one hand: ready access to water; and high quality built structure. It seems that if these two factors were combined and only then was anything else required, then the definition would be proper.