How do I re-hide the bar with "View, Tool, Item"?

Question

I clicked the arrow that popped this out, so now how do I put it back?

Answer 1

It's named Sidebar. There is three ways to hide it:

1. Drag the corner of sidebar to the right:

2. View3D > Menu > View > Sidebar (visible if checked):

3. Shortcut: N, as mentioned in the previous screenshot.