Depending on the issuing country of your passport, transit visas may be required for any given connection in your itinerary. It is your responsibility to secure all travel documents necessary for your trip!
Most of the time airport transit visas are needed when travelers have to transfer from one terminal to another in a foreign airport, when baggage needs to be claimed then rechecked in an overseas airport, or if passengers split their international itinerary into several separate bookings.
Contrary to expectations, sometimes an entry visa may be required even if you only need to leave the arrivals terminal to access a different one within the same airport. Please, thoroughly check all the visa requirements for all the countries in your itineraries.
If you are not sure whether you need a transit or entry visa for any of the connections of your route, please contact the respective country’s embassy, consulate or, otherwise, reach out to the appropriate immigration authority of that country.
Please also review this FAQ: What travel documents do I need for my trip?