If you're flying to or within Europe, please remember that the European Union has stronger consumer protection laws than the U.S. does. They're enshrined in EU 261 and they could get you substantial compensation if your flight is delayed or canceled. The rules break down who is eligible based on length of flight, whether it's within the EU or international and length of delay.
Our British Airways flight in May arrived 3 1/2 hours late in London, which forced us to rebook a missed flight we were to catch to Venice. Because we had a long flight and the delay was over 3 hours, we were eligible for EU261 compensation.
The airline will NOT volunteer this information. You need to know to ask for it. I found the BA website for filing claims, provided dates, flight number, delay and ticket confirmation and asked for the compensation due under EU261.
BA didn't blink an eye. Within days I had $600 US in my bank account! (Personally, I think BA paid less than EU261 specifies, but I decided not to push it further.)
The EU 261 in all its nitpicky detail is here: https://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CELEX:32004R0261:en:HTML
It's worth checking.
(PS: Britain adopted EU 261 into its own laws so even after Brexit, this law still applies to the UK.)