Real Estate Broker:
A middle man or agent who buys and sells real estate for a company, firm, or individual on a commission basis. The broker does not have title to the property, but generally represents the owner.

Cooperative Housing:
An apartment building or a group of dwellings owned by a corporation, the stockholders of which are the residents of the dwellings. It is operated for their benefit by their elected board of directors. In a cooperative, the corporation or association owns title to the real estate. A resident purchases stock in the corporation which entitles him to occupy a unit in the building or property owned by the cooperative. While the resident does not own his unit, he has an absolute right to occupy his unit for as long as he owns the stock.

Encumbrance:
A legal right or interest in land that affects a good or clear title, and diminishes the land's value. It can take numerous forms, such as zoning ordinances, easement rights, claims, mortgages, liens, charges, a pending legal action, unpaid taxes, or restrictive covenants. An encumbrance doesn’t legally prevent transfer of the property to another. A title search is all that is usually done to reveal the existence of such encumbrances, and it is up to the buyer to determine whether he wants to purchase with the encumbrance, or what can be done to remove it.