This is a vector file that represents tax parcels boundaries in Monroe County, New York. According to § 102. Definitions (of the Real Property Tax Law of New York State):

"Parcel" means a separately assessed lot, parcel, piece or portion of real property, except publicly owned bridges and land used for street, road, highway or parkway purposes. A parcel shall not be bisected by a municipal corporation boundary line except that in a special assessing unit a parcel may be bisected by a school district or village boundary line.

For more information on parcels, see the "Parcel" feature class in the RPS_Parcels feature dataset that is maintained by the Monroe County Real Property Services (RPS) department from which this layer was created. The difference between this parcel feature class and the RPS parcel feature class is the latter is updated daily by RPS staff by digitizing new parcel features and does not contain assessment roll data. This layer is recreated biannually by DES staff by joining RPS parcels with the same assessment roll data used to create the Base_County_Parcel_Centroids feature class.