The Internet itself was, or is, a particular network within this large jumble, however, it's name has now come to mean the whole thing. Generally speaking, anyone with access to internet will have an internet address. So anyone who has access to internet should be able to send mail to anyone else who has an internet address. No fucking around, just put their email address on the message and off it goes, automagically finding it's way to the right place. Email address means the type of address i talked about above.
Email means electronic mail - that is, a message sent through a computer system or network.
Email is probably the most used service available to internet users. A large number of internet computers have public file areas and allow anyone to get copies of the files using ftp. The main types of file available, which are of interest to us, are software and text files. If you've got access to ftp, you've got a massive international archive at your fingertips. Material on pretty well any subject you can imagine is there for the grabbing - finding where it is, of course, is another story altogether.