You should be able to find the conditions on the airline website. Most of the conditions might be different from an airline to an other but you also have rights which are not airline-dependant. The one you might be interested in is EU261.
Terms and conditions for RyanAir, for instance :
9.2.2 If your flight is cancelled or delayed for at least two hours, ask at the check-in counter or boarding gate for the text stating your rights, particularly with regard to compensation and assistance. (click here for the text setting out these rights)
See also Easyjet regulations pertaining to flight delays and cancellations.
Credit:stackoverflow.com‘