These computers can transfer information to one another at various speeds depending on how they are linked. No matter how they are linked each of these computers has it's own unique address in the system and is running 24 hrs a day. Servers may be owned by educational institutions, government entities or business. There are many more servers these days with the move toward local access to keep phone bill costs to a minimum. You will have a charge for the server service and telephone charges depending on the distance to the server.
Email is the most widely used service offered on the Net.
Almost all college professors, students, and many government agencies have email access. You can ask a question of a researcher in a field of your interest no matter where they might be located across the world. Library access is now available from many larger universities around the country. Newer information is now being made available very quickly while older studies may not be in electronic form for some time due to the cost and time involved in transferring it from paper to electronic format. You will need an address to find these areas and there are search services available for you to seek out topics or source addresses.