Private & Public Restrictions on Real Estate

Private restrictions on real estate include covenants, conditions, and restrictions (CC&Rs); liens; easements; profit a prendre; adverse possession; and encroachments. CC&Rs are restrictions on how property owners can use their land. For instance a homeowners association in a neighborhood may have a no cars left out on the street overnight policy. Or homes built may have to meet certain criteria, for instance the color may have to be approved, or the garage may have to be in the back yard/ further back from the face of the house. A lien is a claim on a piece of property used to fulfill an obligation or to serve as collateral on debt. An easement is a right given to access the property by the landowner. For instance utility companies may need to access a power line in your back yard so you allow them to walk through. A profit a prendre is an interest in real property that allows one to remove things from the land, like cattle, soil, or produce. Adverse Possession is when an individual who has openly possessed the land for a long amount of time without actually owning the land aquires the title to the land. An encroachment is typically the result of carelessness when a fence line is built over your property line, etc.
An example of an easement would be the Corpus Christi Seawall.  The state of Texas has a public easement of 200 feet along all Texas Beaches.  The depleting beach front over the years has left the private seawall within that boundary.  It was brought to the state and any further plans to expand the seawall were put to rest, but the existing seawall remains private.  This Caller Times article explains further, as well as some alternative land restrictions faced on the beaches of Corpus Christi. http://www.caller.com/news/2008/apr/20/seawall-divides-city/?print=1

Public restrictions on real estate are when the government creates limitations on real estate like taxation, eminent domain, police power and escheat. 
An example of when eminent domain was used was for the expansion of the 610 Loop in Houston. The Texas Department of Transportation bought some 73.4 acres along the West Loop for expansion.  The article explains further. http://realtynewsreport.com/2012/05/14/deal-sikes-unprecedented-eminent-domain-play-in-nw-houston/