When working with computers it can sometimes be beneficial to be able to view two windows next to each other. This can be to compare information in two different windows, or just to be able to use two windows without having to access them from the Desktop each time. In macOS High Sierra, two windows can be displayed next to each other using the Split View feature:
By default, all open windows are layered on top of each other, with the active one at the top
Press and hold on the green maximize button to activate Split View.
The active window is displayed on the left-hand side of the screen, with thumbnails of the other open apps on the right-hand side
If you click once on the green maximize button this will display the app in full-screen mode, rather than holding on it to activate Split View.
Click on one of the apps on the right-hand side in Step 2 to add it as the other Split View panel. Click on each window in Split View to make it active
Drag the middle divider bar to resize either of the Split View panels, to change the viewing area
Move the cursor over the top of the window of each Split View item to view its toolbar and controls
You can work in one panel in Split View (i.e. move through web pages) without affecting the content of the app on the other side.
Swap the windows in Split View by dragging the top toolbar of one app into the other window.