How can I rotate the screen of a MacBook Pro 90 degrees?

How can I rotate the screen of a MacBook Pro 90 degrees to read content like books?

Solution 1:

1. If System preferences is open, close it (this only work once after opening system preferences. I have no idea why)
2. press and hold option/alt + cmd + left click 'Display'
3. Now there should be a button that says 'Rotation: Standard', click it and choose your rotation

Word of caution - it may be tricky to navigate the mousepad with a rotated screen. You feel drunk.

Solution 2:

Hold the Option and Command, click on Preferences and then on Display while holding the Option + Command. Only than you'll be given the option to change the rotation of the screen.