on this day

 on this day  is a feature on some silos and indieweb sites which show posts published on the current (typically Gregorian) day of the year in previous years; commons sites tend to show more general historical events that occurred on that same day.

This week is an alternative that expands this out to show posts from the week around today in history. Many silos and sites offer this broader option for their memory notifications.

Why
Cory Doctorow has an extended essay The Memex Method about why one might want this feature aside from the reminiscent or entertainment aspects.

For more than a decade, I’ve revisited “this day in history” from my own blogging archive, looking back one year, five years, ten years (and then, eventually, 15 years and 20 years). Every day, I roll back my blog archives to this day in years gone past, pull out the most interesting headlines and publish a quick blog post linking back to them.

This structured, daily work of looking back on where I’ve been is more valuable to helping me think about where I’m going than I can say.

Eddie Hinkle
added "This Day" to his site on 2017-03-22. It checks if the month and day of the post match the current month and day without matching the year. If that is the case, it adds a "Flashback card" to the top of the homepage.

Jonathan LaCour
added "Over the years..." support to his site on 2017-04-20
 * current day: https://cleverdevil.io/onthisday/
 * specific day: https://cleverdevil.io/onthisday/04/16

Chris Aldrich
added an On This Day feature to his site using the Room 34 Presents On This Day plugin for WordPress. It has a configurable widget which he added to his home page on 2018-07-18 as well as a separate archive page at https://boffosocko.com/archives/otd/

Colin Walker
has an "On This Day" link at the bottom of his home page that when clicked will display links to historic posts made on the particular day. It uses his On This Day plugin code for WordPress which he's made available on GitHub.

David Shanske
has built on this day functionality into his Tempus Fugit plugin for WordPress
 * example specific day: https://david.shanske.com/onthisday/02/08/
 * current day: https://david.shanske.com/onthisday/

Due to the fact he does not have a post on all 365 days of the year, he also added This Week, which shows posts from this week in history.


 * example current week: https://david.shanske.com/thisweek
 * example week: https://david.shanske.com/thisweek/22 reflecting week 22 of the year.

Alan Levine
Alan Levine built WP Posted Today a WordPress plugin that provides a shortcode for displaying posts published on the current day (or even pre-defined days). Examples of the plugin in use:
 * Alan Levine at https://cogdogblog.com/this-day/ and https://cogdogblog.com/this-day/jan-15/
 * at http://collect.readwriterespond.com/otd/
 * John Johnson at http://johnjohnston.info/blog/on-this-day/
 * since January 2019 at https://www.zylstra.org/blog/today-in/ and also (with a small code tweak to Alan's plugin) as a sidebar widget on every page.

Christopher Finke

 * Christopher Finke wrote an article "https://www.chrisfinke.com/2018/12/18/run-your-own-open-source-timehop/ Run Your Own Open-Source Timehop]" about Clockback an open source project on GitHub.

Jeremy Cherfas
Jeremy Cherfas added an On This Day widget to the sidebar of his Grav-powered site on 2021-07-25. It compares day and month, excluding listens and posts of the same year.

Frank Meeuwsen
added the Tempus Fugit plugin from David Shanske to his WordPress site. It can be found on the On This Day page and widget.

capjamesg
created a "Time Machine" feature on his website with the same intent as "on this day". This feature shows what posts were created on the same day of the month or same day of the year as the current day. The "day of the month" only applies to posts that were created at least six months ago. The time machine page is available here: https://jamesg.blog/search/?time_machine=true

Ghacks
Ghacks technology blog shows a "This Day In History" section both at the bottom of its home page with links to articles published the same day but in previous years.

Wikipedia
Wikipedia has a "On this day…" feature on its homepage:
 * https://en.wikipedia.org/wiki/Main_Page#mp-otd-h2 which links to articles for the current, prev, next days listing historical events that occurred on those days.

Facebook
Since 2018-06-11, Facebook provides a Memories page (login required) with highlights of the past. This builds upon and includes their previous On This Day project.

Facebook provides a notification that:

"You have memories with Person1, Person2, and Person3 to look back on today."

If you choose to share that post, it will post a "memory" X years ago to the audience chosen.
 * FB X Years Ago.png

If you click on the notification or go to the "On This Day" section of the mobile app, it shows clusters of posts that same day, sparse by year: You can access the "On This Day" section of the mobile app by tapping on the "Menu" button in the lower right hand of the tab bar, then scrolling down in the "Explore" section until you find the "On This Day" item.
 * on this day.png

With contents like:
 * friendiversary
 * "You became friends on Facebook with 3 people" clustered header
 * Person (icon, profile linked name, jobtitle at org, [Message] button)
 * posts you published that day
 * looks like entire post is shown, rather than just a summary / excerpt / link-preview

Google Photos
Google Photos makes a little collage of images that links to a set of photos, and notifies you.

Example:
 * google-onthisday.jpg

The mobile app also has a feature intermixed within their other stream-like features (albums, movies, animations, assistant, stylized photos) called "Rediscover this Day" in which they present a few photos from a particular calendar day (usually within a week of the current date X years ago). They also provide a link to an album of all the other photos taken from that particular day. One may have multiple cards in their stream covering various days X, Y, Z, ... years ago to cover different years in the past.

Example:
 * rediscover_this_day.png

Swarm
Swarm just (2017-04-07?) started showing "year ago" notifications:



Which takes you to viewing a checkin with a photo from a year ago, with no other special UI or banner of number of years except for a wide button at the bottom: "Show more check-ins from that day >"

Activating that button takes you to a check-in history search result for your checkins for that day, reverse chronologically ordered:



Twitter
While Twitter doesn't specifically have an on this day feature, one can hack their advanced search to provide this sort of functionality:
 * https://twitter.com/search?f=tweets&vertical=default&q=filter%3Afollows%20until%3A2008-05-25%20-filter%3Areplies&src=typd
 * ht: https://twitter.com/waxpancake/status/999699093277442048

Timehop
Timehop is a service that subscribes to your silo accounts, aggregates your time-based posts, and shows them to you in future years on the same month/day of the year.

WordPress

 * Room 34 Presents on This Day is a good solid option that has a pre-built widget as well as a custom archive page for one's website.
 * This Day in History could also potentially be used, but it requires duplicating lots of data and is anti-DRY.
 * has an On This Day plugin available on GitHub.
 * Alan Levine built WP Posted Today a WordPress plugin that provides a shortcode for displaying posts published on the current day (or even pre-defined days).
 * Tempus Fugit creates on_this_day archive pages automatically by visiting e.g. http://www.example.com/onthisday/12/24/ for a specific day or http://www.example.com/onthisday/12/00/ for the month.

Micro.blog
created - https://github.com/cleverdevil/micromemories - which enables any Micro.blog website to add an "On This Day" page simply by pasting in a little bit of markup. Examples:


 * http://cleverangel.org/on-this-day
 * http://manton.org/on-this-day

Negative reminders
"On this day" can notify you of a personally negative event from a year (or more) ago, thus causing you to potentially re-experience the emotional context surrounding it, which may result in an unpleasant experience.

This has most notably happened with Facebook's implementation of "on this day" and similar "share a memory" features
 * https://twitter.com/PatrickGerard01/status/1031920228098355200
 * https://twitter.com/wonderland449/status/1031972081171423232
 * https://twitter.com/alanjameswords/status/1031956709755899904

Partial possible mitigation: "On this Day Preferences" with filters for specific people or dates: 

Similarly Apple has an iOS feature called "Best of Last Week" that highlights photos from the past week or so, and sometimes errantly provides negative reminders:
 * https://twitter.com/laurenoffwhite/status/1031978308240519168

Timehop added a feature on 2019-01-25 called Hide-a-memory which allows users to click a menu option on each post within their daily history to see it in its original context or to hide it from future display. The main settings will also show how many posts are hidden on an individual day so they could presumably be added back into rotation.



Screenshot of Timehops new feature being unveiled.

Reminders of subsequent loss
"On this day", especially many years later, could also show you positive content that has obvious context, some of which you may have lost since then. E.g.
 * from a past relationship
 * with people or pets who have passed away
 * from a place or home you had to leave
 * ... etc.

Such reminders, especially with images (photos), can provoke or remind you of an unhealthy sense of craving or yearning for something you have lost, even things you thought you had let go of and moved on from.

Temporal window or barrier
Possible global mitigations for negative reminders or periods of time:
 * temporal window (only show past N years of posts on this day)
 * temporal barrier (only show posts "on this day" back to a specific YYYY-MM-DD and no earlier)
 * temporal mask (do not show posts "on this day" during a specific time period date1..date2)
 * hashtag mask (do not show posts "on this day" that have been tagged with a specific hashtag)

Muting or forgetting
To mitigate potential issues of negative reminders or reminders of subsequent loss, content shown in an "on this day" aggregation could have a few options:
 * ( Mute ) - hide this item like you might hide sensitive content by default (but still have a way to reveal / show more. Or mute for some number of years.
 * ( Forget ) - drop this post from any future "on this day" aggregations. Human memory forgets, perhaps this is a feature we need to build into artificial memory systems like "on this day".
 * Should this also unlist the post from any temporal archives and other lists like tag/search results? I.e. the only way to access the post would be via its permalink, which could then have a feature to "re-show" the post in lists (archives, tag/search results, on this day)

Ordinal Day
undefined if I implement this (which I’m considering for Falcon), I will implement it with ordinal day of the year instead of Gregorian day, which will trade February 29th only happening once every four(ish) years with day 366 only happening every four(ish) years.

Summary
"On this day last year, you wrote X posts from Y different locations"

is interested in a summary / recap feature for his website.

Highlighting a Post
If you have made multiple posts on this day in previous years, perhaps just one could be highlighted.
 * The most replied-to post
 * The most retweeted post
 * The most liked post

Home page box
Similar to a box that shows a summary of recent (perhaps 3) articles on the home page, it may make sense to have a show-only-if-there-are-any box that summarizes the most recent (perhaps 3) on this day posts from previous years, with a link to "View more" that links to the /onthisday page listing all such posts.
 * undefined is considering this

Impact on posting behavior
Having reflected on how I’d want to implement On This Day, I have found that just thinking about how to make it work has affected how I now post - undefined. E.g.
 * Date-tagging posts about past events (e.g. TBT, FBF posts), for example #2018_174, so they can theoretically be automatically found by an On This Day feature that checks for the hashtag of that day as well as post created/published/updated dates.
 * Considering posting past photos only a day's worth at a time - so that I can date hashtag them with a precise single date, to provide a more precise On This Day experience in the future.