Threaded messaging is fairly self-explanatory -- instead of having to start a new message every time you want to send a photo or video to someone, you can go ahead and send them right in an existing conversation. You can also now snap a quick response photo in the thread itself and name your messaging groups if you want to differentiate one Direct message group from another.
As for the kinds of photos and videos you can send, that previously only included your own content. Now, however, you can also share pretty much anything you see on Instagram -- perhaps a funny picture your friend took at a party or a video of cute kitten -- as a Direct message. You can do so by tapping a curved arrow (it's located right next to the heart and comment icons) underneath the Instagram post. This will prompt open a Direct message window. Simply enter in who you want to get the message, hit send, and away you go. On the recipients end, when they see the sent image, they can tap it to view the original post. Aside from individual Instagram posts, you can share hashtag and location pages too.
And don't worry about people sharing any of your private photos -- your privacy settings will remain intact. Only those who are permitted to see the image will be able to see it, regardless of who the sender shared it with.
So if you're one of the 85 million people who are into Instagram Direct -- or maybe you want to try it out now that you know its new features -- the latest Instagram update will be available on both Android and iOS starting today.