A Name Server (Nameserver) is a program or computer that translates names from one form into another. For example, a DNS or "Domain Name Server" (also called a "host server") performs the mapping of domain names to IP numbers.
Navigation refers to the system that allows visitors to a website to move around that site. Navigation is most often thought of in terms of menus, but links within pages, breadcrumbs, related links, pagination, and any other links that allow a visitor to move from one page to another are included in navigation.
Nesting refers to putting one HTML element within another element. When this is done, the elements have to be closed in the reverse order from how they were opened.
A non-breaking space (also referred to as ) is a white-space character that isn’t condensed by HTML. It’s primary function is to hold open table cells or add spacing between words (or a the beginning of paragraphs if an indent is desired).