In the real-world library, I search online for a book, reserve others for future reading, check-out the book electronically, and have up to 21 days to read it. It is exactly like purchasing books, except I cannot build up a back-log of reading.
I pay the entry fee through my property taxes. The library card was free.
The reservation issue is less with an online system. I check for new books often, and so I usually either get the books I am looking for, or have a very short wait.