Which of the following describes nonconforming properties?

Nonconforming properties refer to those that were legally established under previous zoning laws but do not comply with the current regulations. These properties often retain their use and structural characteristics even though they do not align with the existing zoning requirements. The term "grandfather clause" is commonly used in this context, allowing such properties to continue operating despite changes in the regulations.

The other options present aspects that do not connect directly to the concept of nonconforming properties. Properties that comply with current laws are, by definition, conforming properties. Newly constructed properties typically comply with current zoning regulations, making them conforming as well. Finally, while properties intended for commercial use may or may not be nonconforming, their use alone does not define the property as nonconforming without considering whether they align with current zoning laws. Thus, the clear connection to the usage of "grandfather clause" makes it the correct choice for describing nonconforming properties.