Anyone who works with computers learns to fear their capacity to forget. Like so many things with computers, memory is strictly binary. There is either perfect recall or total oblivion, with nothing in between. It doesn’t matter how important or trivial the information is. The computer can forget anything in an instant. If it remembers, it remembers for keeps. This doesn’t map well onto human experience of memory, which is fuzzy. We don’t remember anything with perfect fidelity, but we’re also not at risk of waking up having forgotten our own name. Memories tend to fade with time, and we remember only the more salient events. Every programmer has firsthand experience of accidentally deleting something important. Our folklore as programmers is filled with stories of lost data, failed backups, inadvertently clobbering some vital piece of information, undoing months of work with a single keystroke. We learn to be afraid. And because we live in a time when storage grows ever cheaper, we learn to save everything, log everything, and keep it forever. You never know what will come in useful. Deleting is dangerous. There are no horror stories—yet—about keeping too much data for too long. Unfortunately, we’ve let this detail of how computers work percolate up into the design of our online communities. It’s as if we forced people to use only integers because computers have difficulty representing real numbers.