Restoration represents a property at a certain point in its history while erasing evidence of previous times. Preservation is concerned with the upkeep and restoration of existing historic elements, as well as the preservation of a property's shape as it has changed through time. The terms are used interchangeably, although preservation usually refers to what is done now, while restoration often refers to what must be done eventually. In conservation science, restoration and preservation are two separate but related concepts. Restoration focuses on the repair or replacement of damaged or destroyed parts of the environment while preservation aims to maintain natural processes in place by protecting them from further damage. For example, restoration of a building that has been demolished for redevelopment will usually include reconstruction of some or all of the original features, while preservationists may want to protect the building's foundation so that it can be reused in another project. Environmental restoration is the work of conservation scientists who attempt to restore degraded or disturbed areas of land and water bodies to their original condition or better. Restoration can be defined as the act of restoring something that is missing or destroyed. This might mean repairing a building after it has been destroyed by fire, or it could include creating new artwork using materials found in an old quarry. Where restoration involves replacing old parts of the environment with new ones, this is known as remediation.