Redevelopment is any new construction on a site that has pre-existing uses. It represents a process of land development uses to revitalize the physical, economic and social fabric of urban space.

Variations on redevelopment include:

Redevelopment projects can be small or large ranging from a single building to entire new neighborhoods or "new town in town" projects.

Redevelopment also refers to state and federal statutes which give cities and counties the authority to establish redevelopment agencies and give the agencies the authority to attack problems of urban decay. The fundamental tools of a redevelopment agency include the authority to acquire real property, the power of eminent domain, to develop and sell property without bidding and the authority and responsibility of relocating persons who have interests in the property acquired by the agency. The financing/funding of such operations might come from government grants, borrowing from federal or state governments and selling bonds and from tax increment financing.

Other terms sometimes used to describe redevelopment include urban renewal (urban revitalization). While efforts described as urban revitalization often involve redevelopment, they do not always involve redevelopment as they do not always involve the demolition of any existing structures but may instead describe the rehabilitation of existing buildings or other neighborhood improvement initiatives.

A new example of other neighborhood improvement initiatives is the funding mechanism associated with high carbon footprint air quality urban blight. Assembly Bill AB811 is the State of California's answer to funding renewable energy and allows cities to craft their own sustainability action plans. These cutting edge action plans needs the funding structure; which can easily come forward through redevelopment funding.

Some redevelopment projects and programs have been incredibly controversial including the urban renewal program in the United States in the mid-twentieth century or the urban regeneration program in Great Britain. Controversy usually results either from the use of eminent domain, from objections to the change in use or increases in density and intensity on the site or from disagreement on the appropriate use of taxpayer funds to pay for some element of the project. Urban redevelopment in the United States has been controversial because it can displace poor and lower middle class residents, often transferring residents' land and homes to developers for free or a below-market-value price. This is done on the condition that the developer will use that land to construct new commercial and residential developments.

The residents displaced by redevelopment are often undercompensated, and some (notably month-to-month tenants and business owners) are not compensated at all. Historically, redevelopment agencies have been buying many properties in redevelopment areas for prices below fair market value, or even below the agencies' own appraisal figures because the displaced people are often unaware of their legal rights and lack the will and the funds to mount a proper legal defense in a valuation trial.^{[citation needed]} Those who do so usually recover more in compensation than what is offered by the redevelopment agencies.