The answer to 'what is fence' is a barrier or enclosure, typically made of wood, metal, or other materials, that is used to mark the boundaries of a property, contain animals, or provide privacy and security. Fences come in a variety of styles, materials, and heights, and can be used for both functional and aesthetic purposes.
Fences can be constructed in many different ways, such as with posts, rails, and pickets, or with panels and gates. They can be used to enclose a yard, garden, or other outdoor space, or to separate different areas of a property. Fences can also be used to control access to a property, deter trespassing, and provide a sense of privacy and security.