Having two windows or tabs side-by-side on your screen is useful for drag & drop, taking notes, comparing documents, or otherwise multitasking. Here's how to do it on your Chromebook.
1. Resize your current window by going to the top right corner and clicking the middle button to take it out of full-screen mode.
2. Click and hold on the solid bar at the top of your window (next to where tabs are) and drag it to one side of your screen. Don't stop until your mouse touches the edge of your screen and you see a rectangular "shadow" image cover half your screen:
3. Let go of the mouse. It should now dock that window to the side of the screen.
4. Repeat that process with any other window - Chrome or another application - on the other side of the screen. In this example, I am docking my "Files" app to have access to my Downloads.
Bonus #1: You can do this with Tabs in Chrome too! Just click and hold the tab and drag it out of the window and to the edge of your screen.
Bonus #2: The keyboard shortcut to accomplish this is Alt + Square Brackets:
Dock to left side: Alt + [
Dock to right side: Alt + ]