January 1 is also a holiday.
As for time off around Christmas, there is no general practice.
Student or Learner
I understand that 25 Dec is a holiday, how about the other days before and after 25 Dec? Are there any other holidays besides 25 Dec?
Do people usually take leave before or after Christmas in USA? What dates?
(I am not living in the US. Just want to know more about the culture.)
Is boxing day Dec 26 a holiday?
Not in the US, although Boxing Day is celebrated in the UK, Australia, Canada, and several other former British colonies.
Prior to Christmas on the 25th, some people observe Advent, which starts on the 4th Sunday before Christmas (usually end of November or first part of December). Other people observe Christmastide, or the 12 Days of Christmas for a period of about 12 days after December 25th.
However, all of these are Christian religious holidays, so observation practices (including dates and lengths) vary by denomination, and aren't celebrated by non-Christians. Some denominations of Christianity may not observe them either, or place little significance to them.
If you wished to take time off to observe them, you'd have to use some kind of personal or vacation leave, since they're not federally observed holidays.
As Mike said, there's no standard practice, but most business shut down all or part of Christmas day. Many companies or organizations do give employees at least a few days off around Christmas and perhaps again for New Year's, but that varies widely.
I work for a college, and we happen to get off Dec. 24th - Jan. 3rd. Again, that's just my particular college, and I'm pretty fortunate to get that lengthy of a paid holiday.
Wear short sleeves! Support your right to bare arms!
Is 24 Dec a full working day?
In manufacturing environments, it is or was common for factories to be shut down between Christmas and New Years. This allows for maintenance of equipment and allows for the large number of people who want to take the time off for vacation. (A similar week shutdown is usually scheduled in July.)
A lot of people save their vacation time and take off all or most of the days between Christmas and the New Year. Depending on the day of the week of Christmas, a lot of people will start early as well. I began my holiday on Dec 23. A lot of people didn't work at all this week.
My company gives us Dec 24 and 25 as paid holidays, as well as January 1. Most people I know are taking Dec 28-31 as vacation days. I'm taking Dec 28 as a vacation day and working the other three days.
I'm not a teacher, but I write for a living. Please don't ask me about 2nd conditionals, but I'm a safe bet for what reads well in (American) English.