If you arrive at the airport, checked in on time, have all of your flight documents, passport, visa (any applicable), conducted yourself reasonably and followed all of the airline’s procedures correctly, you may have been denied boarding and could be entitled to compensation.
The amount of compensation you can claim for being denied boarding depends on the distance of your scheduled flight, as well as the amount of time lost due to being denied boarding. Overbooking flights is common for airlines. In the event of an overbooking, the airline will ask passengers to give up their seat voluntarily. If there are not enough volunteers, passengers will have to be denied boarding against their will, and this can give rise to a claim for compensation.