This is when something is transmitted by attaching itself to something else that’s travelling.
For millennia ‘data’ was transmitted by being carried by some physical medium. Data always even only ‘existed’ as an attachment to a physical medium. Cave drawing, hieroglyphics, when we write on a piece paper.
Now we have grown out of expecting that data can only be transmitted that way. When we send a text message we don’t type it on our phones and send the phone to the recipient. Right?
Why then do we insist on emailing spreadsheets?