A stopover is essentially an extended connection where you stay in a hub city for more than 24 hours (for international flights) or more than 4 hours (for domestic flights) before continuing to your final destination. Unlike a "layover," which is just a brief pause to change planes, a stopover allows you to leave the airport, stay in a hotel, and explore a "bonus" city for one or more days. Many flagship airlines, such as Icelandair (Reykjavik), Emirates (Dubai), and TAP Air Portugal (Lisbon), offer "Free Stopover" programs where you can add this multi-day break to your itinerary without any additional airfare cost. To book one, you typically use the "Multi-City" search tool on an airline's website. This is a highly effective travel "hack" because it allows you to see two countries for the price of one ticket. However, you are still responsible for your own hotel and food costs during the stopover, and you must ensure you meet the visa requirements for the stopover country.