What to do
Check the exact connection time on your booking and look up the minimum recommended connection for that airport if the information is available. Note whether both flights are on the same ticket. Same-ticket connections give you more protection if the first flight is late. Pack anything you will need during the wait into your cabin bag. Decide in advance whether you will stay airside or try to exit and return.

Three practical approaches
First approach is the short layover, usually under two hours. Stay close to the departure boards, go through security or passport control as soon as you land if needed, and walk directly toward the next gate area. Do not leave the terminal. Keep your phone charged and the boarding pass ready. The main risk is a delay on the first flight that makes you miss the second.

Second approach is the long daytime layover, typically three to eight hours. You have time to eat properly, find a quiet corner or even leave the airport if visa rules allow and the return security line is not too long. Store the cabin bag in a luggage facility if one exists and you want to move freely. Set an alarm with plenty of buffer before the next boarding time.

Third approach is the overnight layover. Desks and most shops close. Some airports offer basic sleeping chairs or quiet zones, others do not. If the airline provides a hotel voucher take it when the connection is long enough and the rules allow. Otherwise look for a simple transit hotel nearby or prepare to rest in the terminal with a jacket and eye mask. Check the exact time the terminal reopens for the morning flights.

Cost
Short and long daytime layovers usually cost nothing extra beyond food and possible luggage storage, which is often 5 to 15 euros or dollars. Overnight stays can bring hotel costs if the airline does not cover them, commonly 60 to 140 euros or dollars for a basic room near the airport. Leaving and re-entering the airport may also involve local transport costs. Same-ticket connections protect you from buying a new flight if the first leg is late, which is the biggest potential expense.

Summary
Connection times behave differently and need different preparation. Short ones demand speed and focus, long daytime ones give room to breathe, overnight ones require a plan for rest and closed facilities. Check whether the flights are on the same ticket, pack essentials in the cabin bag, and choose the approach that matches the hours you actually have. A little planning before you fly removes most of the stress when the layover begins.