I simply can't keep up with the pace with which I snap photos. I rarely go through and delete bad or redundant photos. Rarer still, I take the time to create an album of a trip or event. I'm long past the point of ever bringing some semblance of organization to my photo library.
I'd wager that you, dear reader, are in a similar predicament. Because we can't be trusted to keep our photo libraries nice and tidy, Apple has taken it upon itself to bring some structure to our sprawling collections of photos.
How memories are made
With(and ), the updated Photos app features a new tab called Memories. It serves up a handful of auto-generated albums each day, based on a place, people or time period. So far, my memories have featured place-based albums from a specific location (Edgecomb, Maine), a vacation that spanned multiple locations (Philadelphia to Cobbs Creek, Pennsylvania) and theme-based places ("On the Water" and "On the Mountain"). People-based albums have featured one individual as well as an album titled "Together" that features photos of my wife and daughter. Time-period albums feature photos from a single day or an entire year ("Best of the Year 2015").
When you open an album from the Memories tab, you'll see a pleasingly irregular grid of photos, which Apple determined are the highlights. You can click the Show All link to see all of the photos Apple has included in the album. You can also hit the play button at the top of the Photos window to play a slideshow of a Memory just as you can with any other album, complete with an animation theme (Ken Burns, Origami and so on) and music (either a theme from the Photos app or a song from your iTunes library).
What's in a memory
If you scroll to the bottom of a Memory album, you'll see the people included in the memory, a map of where the photos (and videos) were taken and related memories. At the very bottom are two buttons: Add to Favorite Memories and Delete Memory.
The related memories are useful because you'll find albums here that you won't necessarily see on the main page of the Memories tab. That is, the Photos app has more memories than it shows you up front. And you can create your own album of your favorite memories by clicking the Add to Favorite Memories button at the bottom of any Memory album; you'll find a Favorite Memories album in the Albums view of the Photos app.
If you like the layout of the Memory album -- with its title photo, irregular layout and people and map info -- you can give any album the Memory treatment. When viewing an album that you created, click the Show as Memory button in the upper-right corner. While viewing an album in the Memory layout, scroll to the bottom and click Add to Memories to add it to the main page of the Memories tab. You can then go into the album again and click Add to Favorite Memories to add it to the Favorite Memories album.
Sync via iCloud Photo Library
If you have enabled iCloud Photo Library on your Mac and iOS devices, then you can see the same Memories across all of your devices.
On a Mac, open the Photos app, go to Photos > Preferences and click on the iCloud tab. Check the box for iCloud Photo Library to upload your library to iCloud (it can take a while to complete; it's best to run this overnight if you have a large library).
On an iOS device, go to Settings > iCloud > Photos and toggle on the switch for iCloud Photo Library.