I'm heading to Paris for three nights over Christmas. It will be my fourth trip to the city, but my first at this time of the year.

I've come across a fair bit of information on the Christmas markets which is the main reason for going. The largest seems to be on the Champs-Élysées. There's also three at or very close to the Eiffel Tower and a couple around Montparnasse.

Is there a general rule as whether or not the Christmas markets will be open on Christmas Day itself or can I expect them to be closed?

Similarly, I assume almost all shops (other than perhaps convenience stores) will be closed on Christmas Day but will reopen on 26 December. Is this correct?

I will be staying at the Hyatt Paris Madeleine. Any tips to make the most of the Christmas fun (markets, shopping, lights and, to a lesser extent, food) much appreciated.