How flying actually works, before anyone sells you an upgrade

Almost every expensive flying mistake comes from one of four things: buying the wrong fare bucket, misjudging a bag, misjudging a connection, or missing a document rule. These guides deal with each of them in the order you meet them.

Where a rule differs by carrier we say which carrier. Ryanair measures cabin bags at the gate in Porto, Lufthansa usually does not at Frankfurt, and both facts matter when you pack.