Many of us would not refuse to fly in business class, for the price of economy, but only experienced travelers know that this is possible.
But how? It’s very simple 🙂 There are several options …

When you check in for a flight via the Internet (online check-in), the airline can offer you to upgrade to business class. Those pay a little extra and enjoy the comfort. As a rule, the sum of an economy class ticket + business upgrade costs much less than the initial purchase of a business class ticket.

The upgrade is offered only if there are vacant seats in the business class on the flight. The cost of the upgrade is not static, and depending on the number of empty seats and the time remaining before departure, may change. If you didn’t make an upgrade during online check-in, for example, it was too expensive, then you can try again, but at the self-service desk at the airport. Before the departure, the cost of the upgrade, as a rule, decreases.

You can ask to transfer you to the business class at the reception. If this does not contradict the policy of the airline, then the employee will check the availability in and call the amount of the upgrade.
And now about the promised free options …

Some economy class tariffs provide a free upgrade for overbooking .
Overbooking – resale tickets. Almost every flight has more tickets for sale than it can hold. Why is this done? The fact is that not all passengers who buy tickets come for registration, i.e. refuse to travel. Another, quite common situation when a one-way ticket costs more than a round-trip ticket. In this case, the passenger uses only one flight segment, and the second does not come.

If you came to the airport, but at the check-in you were told that the seats in the economy class are oversold, and at the same time your tariff provides for a free upgrade, then you will be transferred to a business class for free. But you shouldn’t hope for overbooking all the time. if the plane will be sold absolutely all the seats, including in the business class, you will have to wait for the next flight. With overbooking, passengers are often the last to check in.

If your flight is overbooking, and your fare does not provide for an upgrade, then you will still be transferred to a business class flights, but with service as an economy, i.e. food, drinks, allowable weight and amount of luggage, etc. will not differ from economy class passengers.