The BGP Route
The BGP route is, conceptually, a “promise” to carry data to a section of IP space. The route is a “bag” of attributes.
The section of IP space is called the “prefix” attribute of the route.
As a BGP route travels from AS to AS, the ASN of each AS is stamped on it when it leaves that AS. Called the AS_PATH attribute, or “as-path” in Cisco-speak.