This week Facebook announced an offline mode, so mobile users can still see new stories in their News Feeds, even when their connections are spotty. Meanwhile, Twitter announced it would start showing ads to the vast majority of people who visit the platform, and a new study shows Snapchat is the fastest growing social network among millennials.

It's time for Social Media Sunday!

Facebook

News Feed's Coming 'Offline Mode'

Facebook announced this week that it would begin rolling out an update to its flagship mobile app that will improve the loading time of News Feed content for users with spotty or slower connections. The update will include the ability to comment on posts even when you're offline.

"As a next step in improving people's experiences on slower Internet connections, we are shipping several changes that will more efficiently show you relevant stories in your News Feed when you're on a slow connection and will let you compose comments on posts when you're offline," announced Facebook on Wednesday.

Facebook is also testing ways to effectively make an offline mode for the News Feed. "We are now testing an update in which we look at all the previously downloaded stories present on your phone that you have not yet viewed, and rank them based on their relevance," Facebook explained. "This way we can immediately display relevant stories you haven't seen yet, instead of showing a spinner while you wait for new stories."

Facebook did not give a release date for the update, for either iOS or Android devices, saying only that it would be testing and rolling out the features "over time" to get feedback from users.

Facebook At Work to Finally Launch

"Facebook at Work," the company's long-awaited version of Facebook for professionals, may finally get an official launch after years of testing. As Reuters first reported, Facebook's workplace collaboration platform, which hopes to challenge popular platforms like Slack and HipChat, is expected to launch "in the coming months," likely sometime in early 2016.

Facebook's Julien Codorniou told the news service that "95 percent" of what's been developed for the flagship Facebook platform has been adopted for Facebook at Work. "You cannot play Candy Crush on Facebook at Work," forewarned Codorniou, identifying the kind of features in the five percent of Facebook that has been cut from its professional side.

The service will be open to any company once it's launched, using a freemium model that will charge a few dollars per month per user for premium extras. Profiles on Facebook at Work will be kept unconnected to existing Facebook profiles, but features like the News Feed, Likes, and messaging will feel familiar for anyone who's already a Facebook user.

Twitter

Pleasing Wall Street With 'Logged Out' Ad Expansion

It's a rare occasion these days when Twitter announces something that investors are happy about, but it happened this week: Twitter announced on Thursday that it would begin showing advertisements to its "logged out" audience, which represents the vast majority of those who visit the social media platform on any given day.

This represents a massive expansion of Twitter's ad reach, and is expected to positively impact the company's revenues accordingly. As Re/code put it, "This is the moment Twitter investors have been waiting for."

About 500 million people visit Twitter every month without logging into a Twitter account (or without having one in the first place).

The company's announcement of this huge addition -- millions more eyes per month for advertisers to reach -- is, however, diminished by the fact that, as non-registered or logged out visitors, this new segment of Twitter's marketing cannot be as targeted or efficient as, for example, Facebook's oodles of active monthly users. Still, it's a start.

More Timeline Tampering

As Motherboard reported on Tuesday, Twitter appears to be tweaking and testing new changes to its Timeline again. And, again, it appears that the changes make Twitter's main feature more like Facebook's News Feed. Specifically, Twitter looks like it's testing ways to break the Timeline's adherence to chronology.

The changes seem to be limited to a few users, as Twitter's experiments often go. The tech blog discovered the changes after several Twitter users tweeted confusion over why their mobile Twitter app's Timeline was "out of order." Later, a spokesperson from Twitter confirmed the "experiment," as another small test to "explore ways to surface the best content for people."

Snapchat

Fastest Growing Social Network for Millennials

This week, Harvard's Institute of Politics released a wide-ranging survey about all things millennial, including their views on presidential politics, ISIS and terrorism, their personal values, and the economy. As the IBTimes spotted, nestled within the exhaustive report was a question about millennials' favorite social media platforms.

Unsurprisingly, the vast majority of U.S. millennials aged 18 to 29 were on Facebook (81 percent). Facebook-owned Instagram showed a strong second place with 46 percent of millennials.

But Snapchat -- now several years old, and years past its first phenomenal burst on the tech scene -- came in first as far as growth. Since the last time Harvard performed the survey, Fall 2014, 8 percent of millennials have added Snapchat to their social media selection. And with 36 percent of millennials now on Snapchat, the upstart ephemeral messaging platform is on pace to overtake Twitter.

What Harvard couldn't measure was the intensity with which those 36 percent of millennials view Snapchat. But a brief outage this Tuesday, as outraged and insane tweets from Snapchatters, collected by Mashable showed, many of them completely lose their minds if they're not constantly connected.