I used to like to print out our campsite reservations because often, there's no phone service to pull up the email with the confirmation number etc. But our last trip it dawned on me that I could take a screen shot with my phone of the reservation confirmation email, so it would save it on my phone that way and wouldn't require any kind of internet or phone service to view it.
If I'm on a computer, I often use a Print to PDF program so it saves whatever I wanted to print as a PDF, which I can then email to myself, or save as a copy on my phone or laptop. If you email it to yourself or save on a thumb drive, then it makes it easier to print when you actually get to a printer.