I have long ranted against people who confuse the Internet with the (World Wide) Web or social media or basically the part of the Internet they are familiar with.
Well now I no longer have to rant. I can just point people to this: The internet, explained – Vox.
The writers are Vox have done a fine job of explaining what the Internet is. Take a few minutes and read it. I’ve been on the Internet since the late 80s (email was the main use back then). While it is constantly evolving, the fundamental aspects of the Internet don’t change much. Read that piece and you will be good for a few decades.