When you make really big tables in Word that span multiple pages you get into trouble when you try to read the text on the second and subsequent pages of the document because there are no table headings displayed.
Your gut reaction migth be to edit the table and to insert rows for the headings on each of the pages – good idea but there is a better one.
Select the rows at the top of the table that contain the headings – this might be one row or it could be a couple. Now choose Table, Heading Rows Repeat. Voila! Word does all the work for you – it puts the duplicate headings anywhere they need to be – if you add more text to the table or remove text – the headings are always in just the right place – much less effort and a much better end result.