Have you ever searched the web to find an article where you couldn’t see at what date it was published? It happens to me quite often. I don’t understand why such an important piece of information isn’t communicated to the readers.
He goes on to mention putting the date in your URLs, which I do here — the year and month, anyway. And while that’s still a very good idea, since iOS doesn’t show the full URL in Safari unless you have the address bar selected, having it in the URL isn’t as useful as it used to be.
The date on the webpage is a must. And if you publish an update more substantive than a simple typo fix, add the date it was edited too.