A URI (uniform resource identifier) is an extension of the URL. Every URL is a URI, but not every URI can be accessed in the way a URL can. It has the same format as URL, but can also refer to non-information entities such as people or places. The URI acts as a way of refering to the entity so that different information repositories or databases know they are refering to the same thing. For example https://alandix.com/uri/aibook might be used as a way of talking about the paper book. This is used in particular in RDF and other semantic web techologies.
Used on page 386
Also known as uniform resource identifiers