Maybe this is a silly question, but today I was working in my hosts file (C:\windows\system32\drivers\hosts) in notepad++ and would like to use the language formatting.
For example, the first line appears to be a comment
# Copyright (c) 1993-1999 Microsoft Corp.
What language do I choose to view the file?
The hosts file is not written in any programming language. It's simply plain text in a format easily parseable by certain system and network applications. Besides, anyone can come up with a parser that treats text delimited by # as comment lines.
(And in case you didn't get the hint, choose the option that I highlighted in bold.)