On or About is a phrase used to describe a situation where the exact date or time is uncertain but is known to be close to a certain date. It is most commonly used to describe a time period that is approximately a few days before or after a specific date. For example, "The shipment will arrive at or about August 15th" indicates that the shipment could arrive a few days before or after August 15th, but at least close to that date. Another type of On or About is used to describe a location that is close to a certain area, but not necessarily on that exact spot. For example, "The building is located on or about Main Street" indicates that the building is located in the vicinity of Main Street, but not necessarily on it.