Obsidian has two sidebars on both left and right. The left sidebar includes the Ribbon.

Open hidden sidebars

If a sidebar collapsed, you can open it by clicking on the Arrow icon to expand it.

This commonly happens when you enable a plugin but cannot find it anywhere–chances are the new pane created by the plugin is hidden in one of the sidebars. So be sure to check there!

Tabs

By default, plugins will only create new tabs instead of new #Panes.

You can switch between tabs by clicking on the icon. A tooltip will also appear to help you identify tabs.

In each pane, you can only see one tab at every given moment. Some actions will automatically bring a tab into view, for example when you click on a tag.

Close tabs

Some tabs can be closed via the right click menu, but some cannot be closed. If you don’t want to see it, consider disable the relevant plugin or collapse the sidebar by clicking on the Arrow icon.

Rearrange tabs

As of July 2021, there’s no way to rearrange the tabs. If you’d find this handy, echo your voice in this feature request.

Panes

You can have multiple panes in the sidebar.

Create panes

To get a new pane, drag the icon of a tab to above or below a current pane. The highlighted area will indicate where the new pane will be created.

Close panes

To close a pane, you can close all tabs in it, or drag all tabs in it by their icons and drop them into an existing pane.

When only the tab area of a pane is highlighted, the tab being dragged will be dropped into that pane to merge with other tabs in that pane.