Relative timestamp

A relative timestamp answers the question people actually have. In a feed, an inbox, or a comment thread, nobody wants to know that something happened at 14:32; they want to know whether it is new. “Two minutes ago” is read at a glance and needs no arithmetic, no timezone, and no knowledge of what today’s date is. The cost is that the label goes stale while it sits on screen, so it has to re-render on a timer, coarsely: a stamp counting seconds is a distraction, and a stamp that never updates is a lie that gets worse the longer a tab stays open.

The wording is a solved problem and does not need inventing. Intl.RelativeTimeFormat produces the phrase in the reader’s own language and grammar, including the languages where “in three days” is not two words and a number, and its numeric: 'auto' option is what turns “1 day ago” into “yesterday”. Pair it with <time datetime="..."> so the machine readable instant travels with the human readable phrase, and put the full timestamp in the title attribute so hovering gives the exact time. A title is not enough on its own, since it is invisible to touch and unreliable for screen readers, so anything that genuinely needs the precise time should be able to show it another way.

Precision has a threshold, and crossing it is the design decision. Relative wording is useful while the distance is small and becomes useless as it grows: “417 days ago” is worse than the date it replaced. Switch to an absolute date somewhere around a week, keep the year off until the year changes, and never let the two forms disagree. There are also places where relative time is simply the wrong tool. Legal records, financial transactions, schedules, medical logs and anything a person may have to quote back need the absolute time as the primary form, because a stamp whose meaning depends on when it was read cannot be cited. Relative is a convenience for the recent, not a replacement for the record.