What is the cheapest way to travel daily in Doha?

The cheapest way is the Doha Metro and Karwa buses, run by Qatar Rail and Mowasalat. You need a Travel Card (Karwa Smart Card or Metro card), about QAR 10 to buy. A standard single metro trip is QAR 2, with a daily cap of QAR 6 for unlimited standard-class rides. Karwa buses are cashless, so pay with the same card; short trips are about QAR 2.50. Feeder Metrolink buses to nearby areas are free when you tap the card. Top up at station machines, the Karwa app or shops. For daily commuting the card is far cheaper than taxis.