Memories is aiming to be a way for you to look back on the photos you took two years ago today, three years ago today, etc. But it is in a "Stories" form. Which is actually going to be a much better way to check out these photos than how Google Photos was doing it before.
Memories is replacing "Rediscover this Day" in Photos
This feature isn't really new. But the implementation and user interface is new. As well as the name, which actually makes more sense.
Memories is replacing the Rediscover this Day feature that Google Photos has had for quite some time. Where in the Assistant tab, it would bring up cards with pictures that you took on this day, two years ago, three years ago, etc.
It was similar to the "Your Trip to…" cards from when you took photos in a specific city or town.
It wasn't the best implementation of what would be a pretty good feature. As it didn't show all of your photos, and you couldn't see them in full-screen without tapping on them. Which added another interaction. Now with Memories, you tap on it, and it'll move through your photos like it would an Instagram Story.
As expected, this is not going to show you every photo that you took on that day. Instead, Google is using algorithms to choose photos and videos to show you from that day.
Google is also going to allow users to hide specific people or timeframes from Memories. So for instance, if you broke up with your significant other, and don't want to see photos of them in your Memories, you can hide that person. Which is going to be a neat feature.
Yet another app taking Snapchat's original idea and making it more popular
This continues the trend of other apps taking the only feature that Snapchat really excelled with. Which is stories. That's what Snapchat was all about.
Facebook did it first, after Mark Zuckerberg offered to by Snapchat and the company declined. Facebook decided to clone it into all of its apps – Facebook, Messenger, WhatsApp and Instagram.
Then came Google, who added it to YouTube and now Google Photos. Though, with Google Photos, it is a bit of a different feature than what Snapchat and Instagram have.
Google says that Memories will start becoming available today on both Android and iOS. There doesn't appear to be a new update rolling out to the app, so it is most likely a server-side update.