Every quarter, we compile the most important product, commerce, and monetization developments for the major social platforms and explain what they mean for marketers.

Here are the highlights from our Q3 2021 report.

Facebook fights back with a new privacy-focused approach to advertising: In July, Facebook announced it was developing a series of “privacy-enhancing technologies” that aim to limit the amount of personal information it collects from users without compromising ad personalization or measurement.

The announcement comes as Facebook is grappling with the impact of Apple’s iOS 14.5 privacy update, which limits the social network’s ability to track and target users across its apps. Some advertisers have reported that Apple’s new privacy rules are making it difficult to tie Facebook data to actions that consumers take after viewing ads on the platform. That could have long-term effects on ad revenues.

Data on the number of users that have opted in to app tracking on iOS varies, but a recent report from app analytics provider Flurry places it at around 23% of iOS users worldwide.

Instagram focuses on discovery to better compete with TikTok: Many of Instagram’s major moves in Q3—from revamping its search tab and testing a vertical Explore feed to launching ads in Shops—are geared toward better surfacing content and products for users.

One of TikTok’s biggest advantages over Instagram is in discovery, and Instagram knows that its search and discovery tools need to evolve to keep up with TikTok.

Snapchat cements its augmented reality (AR) ecommerce ambitions: Snap is already a popular platform for beauty and fashion brands using AR, but recent moves suggest that Snap is getting serious about expanding its AR ecommerce capabilities.

That includes hiring former Facebook executive Konstantinos Papamiltiadis as its new vice president of platform partnerships, as well as updating its Scan tool and acquiring AR startup Vertebrae.

TikTok takes on everyone else: From in-app shopping and longer video lengths to new creator monetization tools and native ad formats, TikTok has made big moves in Q3 that encroach on competitors’ markets and businesses.

And it’s not just Facebook and Instagram that are feeling the heat: An August report from App Annie shows that time spent with TikTok on Android devices in the US was higher than time spent on YouTube during every month from August 2020 to June 2021.

Twitter makes moves toward more private sharing: Twitter has been experimenting with ways to let users share with smaller groups, segment tweets or followers, and give users more control over how much of their activity is public.

That’s a pretty big shift for a platform based primarily on public sharing, but it could help boost engagement if it makes users more comfortable posting.