Did you know you can use keyboard shortcuts to navigate tabs in the Safari web browser of macOS Sierra? Well, you can.
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Just hold down Command + Shift, then tap the Left and Right arrow keys move through through the browser tabs from left to right or right to left. Or you can hold down Command + Shift, then tap the Open or Close Bracket keys to move through the browser tabs from left to right or right to left.
You can find more shortcuts here.
(This how-to is based on my experiences and info on Apple’s support pages — where the images sometimes come from.)