Google Chrome’s side panel is a new UI for your reading list and bookmarks
Google has introduced a new sidebar feature to Chrome, which lets you quickly access your bookmarks and reading list while using the desktop version of the browser (via 9to5Google). Previously, the reading list’s main home was as a button on the bookmark bar, which not everyone has enabled.
Clicking the side panel button, which looks like a rectangle with a shaded portion on the right side, will show or hide the panel. Once you’ve got it open, you can access the same reading list functions that were available in the old UI, including the ability to add the page you’re currently on to your list, mark items as read, or remove them. You can also switch over to the bookmarks tab to browse your saved pages.