On Snapchat, it's always been about the last 24 hours.
With its requirement that photos and videos shared with friends be taken in the moment, the app has focused on the here and now rather than what you were up to last year or last week.
But the Venice start-up, backed by billions of dollars in venture capital and valued at $16 billion, expanded its offerings Wednesday with a glance to the past.
The company introduced a digital storage bucket, Memories, for users to save their otherwise self-destructing images and resurrect them for future posts. So in the same way Instagram users feel comfortable sharing older memories by describing them as a "late gram" or a "throwback Thursday," Snapchat users now have their own way to bring back old shots. A cloudy border on these pictures makes it clear to friends these are snaps from the past.
Previously captured photos and videos that weren't uploaded to Snapchat before can be uploaded too, with the label "from camera roll."
Memories, accessible by swiping up from Snapchat's photo-taking feature, is one of the most complex additions in the company's five-year history. Snapchat's 150 million daily users, and its many more occasional ones, are expected to receive the new feature in batches over the next month. How they'll perceive the incoming flood of nostalgia isn't certain.
Memories heightens the competition between Snapchat and Facebook, two providers of online communications tools that together control the bulk of time young adults spend on their smartphones. Facebook, which owns Instagram and WhatsApp, is far ahead in that category, but each new feature from Snapchat adds to the pressure on Facebook.
For example, Memories brings Snapchat users many of the capabilities that Facebook's Moments app offers, including easy searches of old photos by location, date or other context clues.
But Snapchat seems to have pushed the bar ahead slightly. Memories, unlike Moments, includes a special, cordoned-off area for photos and videos. Users must enter a PIN to get into the My Eyes Only section. That means a friend helping someone decide which old images should be shared on Snapchat shouldn't come across any nude shots belonging to the smartphone's owner.
Posts saved in Memories are backed up online, giving users more reason to save shots from important life events on Snapchat as opposed to turning to Facebook, Google or Dropbox.
There are some limitations to Memories. Searches pull up only saved Snaps, whereas searches on Moments can include all photos stored on a phone. Using Memories also exposes those saved Snapchat posts, excluding those in My Eyes Only, to release when Snapchat receives a government order to turn over a user's data.
12:42 p.m.: This article has been updated with additional details.