A rule that's over a century old

The first-sale doctrine is a foundational piece of copyright law: once you legally buy a copy of something — a book, a record, a movie — the copyright holder's control over that specific copy ends. You can resell it, lend it, give it away, or destroy it, and nobody needs the original seller's permission. It's why used bookstores, video rental, and libraries are legal at all.

Why digital purchases don't quite work the same way

First-sale rights attach to a physical copy changing hands. A digital "purchase" usually isn't a copy changing hands at all — it's a license being granted, governed by a click-through agreement most people never read. That agreement typically says the license is non-transferable, revocable, and tied to your account, not a piece of property you own outright.

The practical effects show up constantly: you can't resell an ebook the way you can a paperback. A "purchased" digital movie can be pulled from your library if the store loses distribution rights. A game exists only as long as the platform's servers and your account stand.

Why it matters even if you never plan to resell anything

Even people who'd never dream of reselling a digital purchase are affected, because "you can't resell it" is really shorthand for "you never owned a transferable thing in the first place." The rights that historically came bundled with buying something — resell it, lend it, keep it working after the seller moves on — don't automatically survive the switch from physical to digital. They have to be negotiated back in, and right now, mostly, they haven't been.