An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

# Ignore everything
*

# But not these files...
!.gitignore
!script.pl
!template.latex
# etc...

# ...even if they are in subdirectories
!*/

# if the files to be tracked are in subdirectories
!*/a/b/file1.txt
!*/a/b/c/*