Final answer:
Vendor online catalogs are typically viewed by customers using a browser, which is a software application designed for accessing web content on the internet.
Step-by-step explanation:
Vendor online catalogs can be viewed by customers through a browser. A browser is a software application used to access and view websites and web content. In the context of online shopping, a browser allows customers to visit various vendors' websites to view their products, services, and catalogs. For instance, when you want to shop online, you would open your browser, type in the address of the vendor's website, and navigate through their online catalog. Browsers operate on the internet, which is a public network, unlike compilers which are used for converting source code into an executable program or intranets which are private networks accessible only within an organization.