For reasons I can't fully explain, I had a lot of difficulty wrapping my mind around the economic concept of rent.  Sometimes it came into clear focus, and other times the clarity receded.  I've gathered a bunch of references here in the hope that they will help you achieve — and keep — clarity!

Rent, as the term is used on this website is a bit different from the common usage.  In common usage, we use the word rent to mean the monthly payment to one's landlord for the use of all or part of a building at a particular location.  But good economists are more precise: rent is the annual value of a piece of land, the amount a person who wants to use a particular site owes for the use of that site.  Even if there is an improvement on that site — a parking lot, a house, a high-rise building — the amount one pays for that improvement in that location may be largely land rent.  Think about the market value of a, say, four-bedroom, two bath colonial-style 30 year old home in a small town and an identical home on a similar-sized lot within commuting range of New York City.  They would sell for very different prices, and rent for very different prices.  The difference is a difference in land rent. 

Buildings, by their nature, are depreciating, though an attentive owner can slow that depreciation by continuous maintenance and occasional re-novation. Land tends to appreciate, assuming that the local population is growing and the particular property is located close enough to the center of things to be appealing to a significant portion of the population.

The way economics is taught and much of common usage causes us to conflate land and capital as a single factor of production, when in fact they are completely different from each other. Failing to make the important distinction between land and capital — and therefore between rent and interest, the respective returns on land and capital — leads to all sorts of distortions, inequities and iniquities. Think precisely!

Henry George: The Land for the People (1889 speech)

I said that rent is a natural thing. So it is. Where one man, all rights being equal, has a piece of land of better quality than another man, it is only fair to all that he should pay the difference. Where one man has a piece of land and others have none, it gives him a special advantage; it is only fair that he should pay into the common fund the value of that special privilege granted him by the community. That is what is called economic rent.

BUT over and above the economic rent there is the power that comes by monopoly, there is the power to extract a rent, which may be called monopoly rent. On this island that I have supposed we go and settle on, under the plan we have proposed each man should pay annually to the special fund in accordance with the special privilege the peculiar value of the piece of land he held, and those who had land of no peculiar value should pay nothing. That rent that would be payable by the individual to the community would only amount to the value of the special privilege that he enjoyed from the community. But if one man owned the island, and if we went there and you people were fools enough to allow me to lay claim to the ownership of the island and say it belonged to me, then I could charge a monopoly rent; I could make you pay me every penny that you earned, save just enough for you to live; and the reason I could not make you pay more is simply this, that if you would pay more you would die. 

THE power to exact that monopoly rent comes from the power to hold land idle -- comes from the power to keep labor off the land. Tax up land to its full value and that power would be gone; the richest landowners could not afford to hold valuable land idle. Everywhere that simple plan would compel the landowner either to use his land or to sell out to some one who would; and the rent of land would then fall to its true economic rate--the value of the special privilege it gave would go not to individuals, but to the general community, to be used for the benefit of the whole community. ...  

Now, rent is a natural and just thing. For instance, if we in this room were to go together to a new country and we were to agree that we should settle in that new country on equal terms, how could we divide the land up in such a way as to insure and to continue equality? If it were proposed that we should divide it up into equal pieces, there would be in the first place this objection, that in our division we would not fully know the character of the land; one man would get a more valuable piece than the other. Then as time passed the value of different pieces of land would change, and further than that if we were once to make a division and then allow full and absolute ownership of the land, inequality would come up in the succeeding generation. One man would be thriftless, another man, on the contrary, would be extremely keen in saving and pushing; one man would be unfortunate and another man more fortunate; and so on. In a little while many of these people would have parted with their land to others, so that their children coming after them into the world would have no land. The only fair way would be this-- that any man among us should be at liberty to take up any piece of land, and use it, that no one else wanted to use; that where more than one man wanted to use the same piece of land, the man who did use it should pay a premium which, going into a common fund and being used for the benefit of all, would put everybody upon a plane of equality. That would be the ideal way of dividing up the land of a new country.

That is what we propose by what we call the single tax. We propose to abolish all taxes for revenue. In place of all the taxes that are now levied, to impose one single tax, and that a tax upon the value of land. Mark me, upon the value of land alone -- not upon the value of improvements, not upon the value of what the exercise of labor has done to make land valuable, that belongs to the individual; but upon the value of the land itself, irrespective of the improvements, so that an acre of land that has not been improved will pay as much tax as an acre of like land that has been improved. So that in a town a house site on which there is no building shall be called upon to pay just as much tax as a house site on which there is a house.

I said that rent is a natural thing. So it is. Where one man, all rights being equal, has a piece of land of better quality than another man, it is only fair to all that he should pay the difference. Where one man has a piece of land and others have none, it gives him a special advantage; it is only fair that he should pay into the common fund the value of that special privilege granted him by the community. That is what is called economic rent. BUT over and above the economic rent there is the power that comes by monopoly, there is the power to extract a rent, which may be called monopoly rent. On this island that I have supposed we go and settle on, under the plan we have proposed each man should pay annually to the special fund in accordance with the special privilege the peculiar value of the piece of land he held, and those who had land of no peculiar value should pay nothing. That rent that would be payable by the individual to the community would only amount to the value of the special privilege that he enjoyed from the community. But if one man owned the island, and if we went there and you people were fools enough to allow me to lay claim to the ownership of the island and say it belonged to me, then I could charge a monopoly rent; I could make you pay me every penny that you earned, save just enough for you to live; and the reason I could not make you pay more is simply this, that if you would pay more you would die. 

THE power to exact that monopoly rent comes from the power to hold land idle -- comes from the power to keep labor off the land. Tax up land to its full value and that power would be gone; the richest landowners could not afford to hold valuable land idle. Everywhere that simple plan would compel the landowner either to use his land or to sell out to some one who would; and the rent of land would then fall to its true economic rate--the value of the special privilege it gave would go not to individuals, but to the general community, to be used for the benefit of the whole community.

I cannot pass on without mentioning the name of one of the distinguished Irishmen who have declared for the principle long before they heard of me. I refer to only one name. Many of you know, and doubtless all of you have heard, of Dr. Nulty, the Bishop of Meath.

IN 1881, before I had ever been in Ireland or Dr. Nulty had ever heard of me, he wrote a letter on the Land Question to the clergy and laity of the diocese of Meath. Dr. Nulty lays down precisely the principle that I have endeavored to lay down here before you briefly, that there is a right of ownership that comes from work, from production; that it is the law of nature, the law of God,

• that all men should work;
• that what a man produces by his labor belongs to him;
• that the reservoir from which everything must come -- the land itself -- can belong to no man, and
• that its proper treatment is just as I have proposed to let there be security of possession and to let those who have special privileges pay into the common fund for those privileges, and to use that fund for the benefit of all.

Dr. Nulty goes on to say what every man who has studied this subject will cordially endorse, that the natural law of rent -- that law by which population increases the value of land in certain places and makes it grow higher and higher -- that principle by which, as the city grows, land becomes more valuable -- that that is to his mind the clearest and best proof, not merely of the intelligence but of the beneficence of the Creator. For he shows clearly that that is the natural provision by virtue of which, if men would only obey God's law of justice, if men would only obey the fundamental maxim of Christianity to do to others as they would be done to them: that by virtue of that provision, as the advance of civilization went on, it would be towards a greater and greater equality among men-not a now to a more and more monstrous inequality.  Read the whole speech

Henry George: Why The Landowner Cannot Shift The Tax on Land Values (1887)

Winston Churchill: The People's Land 

Nic Tideman:  Farm Land Rent and the Renewal of Rural Society: The Self-Financing Model

The rent of land is the amount of money that would be bid for the use of land in an auction. It can be thought of as 100 [rubles] more than the second-highest bid, that is, the amount of money that the person for whom the use of land is most valuable must bid to outbid the person who places the second-highest value on it.

Fred Foldvary:  The Rent, the Whole Rent, and Nothing but the Rent

• the spatial surface of the earth,
• material resources such as water and minerals,
• the radio spectrum,
• the atmosphere used for travel or as a dump,
• all wildlife, and
• the genetic information in living beings.

• The pure land rent is the natural rent, the payment for the resource as provided by nature.
• The second component is a rental for the advantages of a site due to the civic works. This is the infrastructure such as streets, parks, utilities, security, schools, and the legal system which makes real estate much more useful. This rental is really a return to capital goods and labor services rather than land.

Everett Gross: Explaining Rent

Sometimes it's difficult for people to understand the meaning of "rent" as an economic concept. One way I have of explaining it doesn't use the word rent. I just use a little analogy.

I'm from Crete, Nebraska. It's a small town of 5,000 people.

Suppose a man comes to Crete, and he wants to start a business. He needs a building, but first he needs a piece of ground to build this new building on. So he looks up a real estate agent, describes what he wants, and the real estate agent shows him a parcel that's just right for his needs. The man asks the agent, "All right, now how much money do you want for this land?" The agent says, "It's worth $50,000." The man says, "Why is it worth $50,000?" And the real estate agent points out that "The school is good, the roads are good, the police department is good, the rescue crew is good and very fast, and business is good here."

So the man says "Yeah, I believe that $50,0000 is a fair price. I'll take it. How do I pay the $50,000 to the school people, and the road people, and the police department? To whom do I pay the $50,000?" And the real estate agent says, "Oh no. You don't pay it to them. You pay it to the person who owned the land before."

The man says, "But who supports the schools, and the roads, and the police, and the other good things?" And the real estate agent says, "If you build, then you'll pay for them again."

The buyer then asks, "And what will the previous owner do for me for my $50,000?"  The real estate man answers, "Nothing!  Nothing at all!"

Now I don't need to use the word "rent" in that explanation. ... see the whole story, including Dave Wetzel's version

Nic Tideman:   The Case for Taxing Land

• Labor can be defined as the factors of production that own themselves. 
• Ownership of capital is derived originally from organizing its production and paying the various factors that are employed to produce it. 
• Ownership of land, by contrast, derives from rights of exclusive use and access that are granted by governments.

Charles T. Root — Not a Single Tax! (1925)

Every community, whatever its political name and extent -- village, city, state or province or nation -- has its own normal, unfailing income, growing with the growth of the community and always adequate to meet necessary governmental expenditure.

To explain: Every community has an indefeasible original right to the land on which it exists, and to all the natural, unmodified properties and advantages of that particular area of the earth's surface. To this land in its natural state, undrained, unfenced, unfertilized, unplanted and unoccupied, including its waters, its contents and its location, every individual in the community (which may consist of any political unit selected) has an equal right, while all the individuals together have a joint right to the value for use which society has conferred upon these natural advantages.

This value for use is known as "Land Value," or by the not particularly descriptive but generally adopted name of "Economic Rent."

Briefly defined the land value or economic rent of any piece of ground is the largest annual amount voluntarily offered for the exclusive use of that ground, or of an equivalent parcel, independent of improvements thereon. Every holder or user of land pays economic rent, but he now pays most of it to the wrong party. The aggregate economic rent of the territory occupied by any political unit is, as has been stated above, always sufficient, usually more than sufficient, for the legitimate expenses of the government of that unit. As also stated above, the economic rent belongs to the community, and not to individual landowners. ... read the whole article

Jeff Smith and Kris Nelson: Giving Life to the Property Tax Shift (PTS)

Bill Batt: The Compatibility of Georgist Economics and Ecological Economics

Bill Batt: Water and Privatization

Bill Batt: The Nexus of Transportation, Economic Rent, and Land Use

What is Land Rent?
John Houseman, an actor perhaps most widely known as Professor Kingsfield in the long-running TV series, The Paper Chase, later became the pitchman for Smith Barney. In that advertisement, his tag line was "We make money the old-fashioned way -- we earn it."

That we should earn our money rather than live off the efforts of others seems a simple enough moral tenet. But it seems to have lost its cogency in contemporary economic thought. More than a century ago John Stuart Mill noted that

Landlords grow richer in their sleep without working, risking or economizing. The increase in the value of land, arising as it does from the efforts of an entire community, should belong to the community and not to the individual who might hold title.(1)

Today, on the other hand, the unearned surplus which classical economists called rent attaches to monopoly titles -- largely the scarce goods and services of nature like locational sites, and has totally disappeared from economic calculus. Yet this is the primary vehicle by which wealth is captured by economic elites. If government recaptured the socially-created economic rent from land sites that comes from the investment of the collective community, we could eliminate other taxes that are both more onerous and create a drag on the economy that makes us all poorer. There are many websites that explain how this can be done, ways that not only beget greater economic efficiency but also bring about economic justice.(2) The surplus economic rent that derives from community effort is its rightful entitlement.

Where does economic rent most tend to lodge? In the center of cities where people are. And also proximate to heavy social investments -- such as railroad and metro stations, public and office buildings, hotels and conference centers, and anywhere there is high traffic in personal or market exchanges. The land value in New York City is higher than all the rest of the New York state combined, even though it is only a minute fraction of the area. One 9-acre site south of the United Nations Building was recently sold to a developer intent on building luxury condominiums facing the East River. That site sold for $680 million, and would have been higher had the existing structure, an obsolete power plant, not have to be razed.(3) Land values in any given area tend to rise and fall together, and tend also to form a contour somewhat comparable to a topographical survey map. In a city's center are the highest value locations, analogous to a mountain peak. Once one departs from that center, land values fall in direct proportion to the value of their use, made more or less attractive by whatever social attributes are provided in the proximate areas. Two illustrations from small and medium sized cities in the United States illustrate the point. ...  read the whole article

Nic Tideman: Market-Based Systems for Assigning Rental Value to Land

Defining "The Rent of Land"

To proceed, there must be agreement upon a definition of "the rent of land." From a conceptual or theoretical perspective, the rent of land is a residual. It is the difference between total revenue and costs other than land, when land is managed in such a way as to yield the greatest present value of net returns.

There are two practical difficulties with this definition. It yields an answer in terms of the present value of rent rather than an annual amount, and it does not provide an algorithm for public officials to follow. The two difficulties can both be overcome by using an operational concept of rent, defined in terms of what people are willing to pay. ... . read the whole article