Apparently (I keep using apparently because no one is certain what the exact origin of this idea is), Millennials, really like nostalgia so they designated a day on which one can be nostalgic and feel part of something at the same time. So, what you do is, you post a picture online, on Twitter, Facebook or Instagram, for example and don't forget the hashtag. A hashtag, for those who throw back to at least my generation, is a word or saying (no spaces) that has a "#" in front of it. Thus, "hashtag."I believe that means you can find other postings with the same hashtag easier, but I haven't tested that theory. So, if you post a photo on Throwback Thursday you might hashtag (a new verb) it, #throwbackthursday or #bt (I trust you can figure that out). The cool thing, they say, is that Throwback Thursday occurs every week -- and that is because, well, there is a Thursday in every week! It's not like you have to wait a year for the holiday or 17 for the cicadas. It's every week!
Now another thing. Whichever picture you post need not have anything to do with Thursday. So, it isn't that you're positing a picture that was taken on a Thursday. Nor does the topic of the picture need to have any connection with Thursday. This could have been Fallback Friday. But I have a feeling whoever came up with it liked having "TH" at the beginning of each word. A little onomatopoeia, if you will.
The picture need only be nostalgic. And probably should be at least five years old because, well, what isn't nostalgic about 2008??
This has become a game on the Interweb, I've learned from my five minutes of research this morning. So, by the time you read this, the game may be over and we may have moved on. To what, I don't know. Maybe Magnificent Monday or Wonderful Wednesday. Or, well, tomorrow.