Parcel information pertains to the smallest unit or lowest common denominator of land ownership. Parcels in land-oriented systems are roughly analogous to cells in an organism; they represent the basic building blocks of larger units and systems.

In general, the land recording function which collects parcel data is undertaken exclusively by government. The concepts and uses for land recording systems can be traced back to the early Roman Empire and are often associated with property tax and property rights systems. The recording of deeds, for example, is one of the oldest and most important record-keeping functions of government.

Each country has some standard for land recording and most land records originate and are maintained at the local level of government. In the United States, a land record depends on documentation (such as a deed), which is evidence of land ownership and ownership transfers. Each state varies in its laws, in the way land is recorded, and also in the terminology used. In 1980, a National Academy of Sciences study estimated that the US has more than "3000 land-title-record systems organized on a county basis and about 500 organized on a city or town basis" (National Academy of Sciences, 1980).

According the Federal Geographic Data Committee (FGDC, 1980), continuing technological changes, coupled with trends in selling and developing land, have opened up new ways of looking at land recording systems. For the past thirty years, local governments have made a variety of efforts to computerize their land recording systems. The extent of computerization ranges from the basic use of word-processing programs to sophisticated web-enabled database applications across multiple departments. A general trend has been to use basic land-recording systems and geographic information systems, as well as other types of database systems to accomplish the goals of local governments (National Research Council, 1983). Nevertheless, in many localities all or nearly all information is collected manually.

In New York, as in most other places, parcel identification, description, and ownership information is collected as a function of real property laws and tax administration. Under New York’s Real Property Law, a state agency, the Office of Real Property Services (ORPS) establishes broad guidelines and qualifications for assessors who appraise and record land. However, these activities are mostly carried out under the jurisdiction of county and municipal governments, which each have their own rules and practices. Typically, deeds are recorded by county clerks as the official record of land ownership and ownership transfer. Assessors employed by cities or towns conduct real property appraisals for parcels located in their jurisdictions to establish their value for purposes of taxation. In addition, ORPS staff conduct direct appraisal of certain types of parcels such as forests. The information about individual parcels is specified in state guidelines and rules and organized into municipal assessment rolls used to prepare local property and school tax bills. Certain information is also transmitted to county real property tax service officials who prepare county-wide assessment rolls and tax maps, again following state guidelines. The final county tax rolls are submitted annually to ORPS. County clerks also provide ORPS with information on real property sales throughout the year. When all assessment rolls are received, ORPS uses this information to set equalization rates intended to fairly distribute local property tax burden across municipalities; counties and municipalities use these rates to calculate tax bills for property owners.

The information that originates with these real property recording and tax functions has great utility for many other uses from school bus routing, to emergency response, to the siting of new businesses, to the protection of green space. These uses and issues related to parcel data are discussed throughout this report.