the airline's bet that your first plane and your legs can both run on time.
means a second flight you catch after a layover, booked as one ticket so the airline is on the hook if you miss it.
from comes from the hub-and-spoke system airlines adopted in the 1970s and 80s after deregulation, funneling passengers through central airports like chicago and atlanta instead of flying direct everywhere.
atlanta hartsfield jackson — world's busiest airport, built almost entirely around connections since 1998
dubai international — emirates routes over 70 percent of passengers through as connections
chicago o'hare — united's hub where a 35 minute layover regularly means an actual sprint
singapore changi — designed so a 90 minute transit still allows a butterfly garden visit