What is a companion ticket and upgrade?

• In the case that you purchase a ticket for yourself, you can get a ticket for the person who will be accompanying you for significantly suitable mile amounts. For each purchased ticket, 1 companion ticket is provided. The person accompanying you must travel on the same airplane as you both ways and on the same or a lower flight class. Companion tickets cannot be upgraded with miles. Miles cannot be earned on flights taken with companion tickets.
• You can upgrade your flight class by using your miles. To upgrade to Business or Comfort Class, you must have a valid and purchased Economy Class ticket which earns you miles and has a confirmed reservation.
• To take advantage of the upgrading services only available on Turkish Airlines flights, you must have a confirmed reservation on Business or Comfort Class. You must upgrade your tickets at least 1 day before the flight. This transaction cannot be performed during check-in or boarding. No upgrades are granted for free tickets and companion tickets.