Microsoft released the latest Windows 10 Insider Preview (Build 21286) yesterday, and with it introduced dynamic content to the taskbar. Don't worry though, you can personalize the content or turn it off completely.
As the Windows Insider Blog explains, the dynamic content feed sits on the right-hand side of the taskbar next to the hidden icons arrow. Mousing over the box triggers the dynamic feed of content to appear, be that news, weather, sports, or other content from over 4,500 global brands. Otherwise, the content remains hidden and you'll just be able to see the current state of the weather viewable within the confines of the taskbar (or some other content you selected).
The idea behind this new feature is to offer a way to access content without having to load and switch between apps. Even clicking on content within the taskbar window loads a streamlined reading view so you can consume it quickly and get back to whatever you were doing beforehand.
The content displayed can be personalized through "More options" where you can choose to see more or fewer stories of a certain type, which over time will influence what new content is shown to you. Tracking by third parties and advertisers can be limited through the Microsoft Privacy Dashboard, and you can turn the dynamic content feature off completely simply by right-clicking on the taskbar.
Microsoft is hoping to add this dynamic content feature elsewhere within the operating system, and the Edge browser is named as one of the first being considered. Of course, how widely the feature spreads will depend on how positive the feedback is from Windows Insiders over the coming days and weeks.