it depends
Yes.
Interconnected, networked
a related group of networked computers forms a DOMAIN.
Networked computers.
Apple Macs and other types of computers can be networked together and can happily share a modem.
networked computers are just normal personal computers connect together businesses usually connect them in a network to fill business needs e.g. to provide Internet or to monitor productivity... so to answer you question most big business will have this and a fair few smaller business will have this setup or will have. The limitations is that in companies the regular users can not add programs and they do not have admin control, so they need their own computers to do some functions and the networked computers are highly monitered, so they may want privacy.
If they are reasonably close together, you can use an "A/B Switch", otherwise you'll need to network them.
An advantage of networked computers is the ability to share resources, such as files, printers, and internet connections, which enhances collaboration and productivity among users. Additionally, networked systems facilitate communication through email and messaging platforms, allowing for real-time interactions. This interconnectedness also enables centralized data management and backup, improving security and efficiency compared to non-networked setups.
A swarm
You can set up new employee logins on your networked computers by going to user settings, and adding users. As well, you can have your IT help you with this.
No - a supercomputer is a single device or system (although fast and expensive). A massive collection of networked computers can give the results of a supercomputer but they would not be considered one.
A computer network - is two or more computers linked together. It's useful - because computers can communicate 'live' with each other. Additionally - If computers are networked, you only need one printer. All the computers on the network 'share' the printer between them.