What is the local property tax based on?

In the United States and Canada the local property tax is based on the estimated value of the property being assessed. It is often called an "ad valorem tax", which is a Latin term meaning according to value. Local assessors are charged the responsibility of inventorying and estimating the value of all personal property (non-real estate) or real estate (land and buildings attached to land) in their community. State or provincial tax laws usually define the type of value estimated (market value, use value, etc.) and the specific date when it is estimated for property tax purposes. For example, in Virginia real estate assessments are estimated as of January 1 or July 1 each year as described by local ordinance. Some types of property are exempt for taxation like government-owned property, and property of religious organizations.