if site has tags or categories

To check if a single post has tags I’d use something like this:

if(has_tag()) { the_tags(); }

same with checking for categories on a single post:

if(has_category()) {}

My question is: I’m having trouble finding how to find out if an entire site/blog has any tags or categories declared yet? Not a specific post..

if site_has_tags() if site_has_categories()

Anyone know how I’d go about doing this?