Detailed answer
Visible text can use a friendly date format while datetime carries a machine-readable value.
Use valid syntax and supply timezone information when representing a particular instant. This preserves meaning without forcing readers to see technical formatting. Publish genuine dates rather than backdating learning posts to imitate historic activity.
Example
<p>Updated <time datetime="2026-10-22">22 October 2026</time></p>
Understanding the behavior
Datetime gives time-related text a machine-readable representation while allowing a human-friendly label. Use a valid value that matches the visible meaning. If a precise moment matters across time zones, include an appropriate offset in a full date-time value.
Practical implementation notes
Do not encode a vague phrase as an invented exact timestamp. For a publication date that only needs a calendar day, a date-only value can be clearer than adding an arbitrary time.
How to check it
Inspect datetime and compare it with the visible date; add an offset when describing a precise instant.
Expected result
The machine-readable value describes the same date or instant shown to readers.
Watch out: A date alone does not identify a timezone-specific event instant.
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