Perl_Programmer1992:

"word": it means it's an underscore, a digit, or a letter.

Note that if you have Unicode strings, \w also includes Unicode's notion of "Word" characters - see Word characters. These are all considered "Word" characters: ξ ᚏ 𫝼 ஹ ᕭ 🅿

By the way, you don't need to include "Beginner in perl" in your node titles :-) (see also How do I compose an effective node title?)