Appraisers and assessors of real estate estimate the value of real property whenever it is sold, mortgaged, taxed, insured, or developed. They work in localities they are familiar with, so they have knowledge of any environmental or other concerns that may affect the value of a property. They note any unique characteristics of the property and of the surrounding area, such as a specific architectural style of a building or a major highway located next to the parcel. They also take into account additional aspects of a property such as the condition of the foundation and roof of a building or any renovations that may have been done. They might take pictures to document a certain room or feature.