Character Classes includes a list of characters included in a square brackets. Matching of any of these characters result in a match of the character class. The characters inside the bracket with the combination of characters outside the brackets are matched for in the string.

    #! C:\programfiles\perl\bin\perl
    print "content-type: text/html\n\n";
    @word=qw(joel joe john pol doe);
    foreach (@word){ 
    if (/[jpd]oe/) 
     {                
       print "Matched !  $_\n";
     }
    else 
     {
       print "Sorry.   $_\n";
     }
     }

    Matched ! joel Matched ! joe Sorry.john Sorry. pol Matched ! doe 

In the above example a list is seperated by space as it is prefixed by the "quote words" its split by words, then in a loop each word is checked to have a pattern "joe" "poe" "doe", because the j,p,d are character classes any of which along with "oe" is matched for in the string.