A more thorough explanation:

Definition: Airspace refers to the space above the surface of land that is necessary for the owner or possessor to have reasonable use and enjoyment of their property. It also includes the area above legally established minimum flight altitudes, which is needed to ensure safe takeoffs and landings of aircraft.

Examples:

• National airspace: This refers to the airspace above a nation's territory, including internal waters and the territorial sea. A country has complete and exclusive sovereignty over its national airspace, and foreign aircraft have no right of innocent passage. For example, if a foreign aircraft enters the national airspace of a country without permission, it could be seen as a violation of that country's sovereignty.
• Navigable airspace: This is the area above the legally established minimum flight altitudes. It includes the space needed to ensure safe takeoffs and landings of aircraft. For example, if a plane is taking off or landing at an airport, it needs a certain amount of navigable airspace to do so safely.

The examples illustrate how airspace is divided and regulated. National airspace is under the control of individual countries, while navigable airspace is regulated to ensure the safety of aircraft.