Final answer:
The unique address of a web page is called a URL, which stands for Uniform Resource Locator. DOIs are used for articles in journals to permanently locate the online source.
Step-by-step explanation:
The unique address of a web page is called a URL (Uniform Resource Locator). It is a specific string of characters that represents the address where a particular page can be found on the internet. Articles in journals may also have a DOI (Digital Object Identifier), which is a persistent identifier system that locates online sources and remains constant, even if the URL changes. It's useful for citing sources, as in academic writing where the format could be author's name, title of the website, and the URL or DOI of the cited material.