Officially we have 11 National Holidays. Christmas, New Years, Independence Day, Thanksgiving and Inaguration Day all celebrate events. Veterans Day, Memorial Day and Labor Day celebrate groups of people. Columbus Day, Washington's Birthday (Also known as Presidents Day) and Martin Luther King Jr. Day celebrate people.
Christmas and New Years are self explanatory along with Washington(Presidents Day), MLK Day and Columbus Day.
Inauguration Day, which is only observed every four years, celebrates the Inaguration of a New President.
Veterans Day honors all Military Veterans.
Memorial Day honors all Veterans that have died in the service of our Country.
Labor Day honors workers but is really just an excuse for getting drunk and cooking out with friends.
Thanksgiving is the day we celebrate the early settlers surviving in the New World after the British screwed them over and left them for dead.
Independence Day celebrates the signing of The Declaration of Independence from Great Britain. (Also sometimes referred to as (Fuck Off you bunch of English Twats Day).
I hope this helps.