Nucleus/core, halo/coma, and tails
The three parts of a comet are the nucleus, coma, and tail.
As I answer this now it is early (6:30 am) on July 19. If you're confused about the date on posts, it's British date because thats where the site server is.
when you asked the question it was the 19 of July but now it's nether for the futter when I answered on 10/10/15