Beyond Advertising

How much of marketing's function is advertising?

As I understand, marketing functions include (but doesn't limit to) advertising, distribution and sales to some extent. But, the more I learn what's described about marketing, the more it tends to be focused towards advertising only. At times, it even feels like both words could be used as substitutes for each other.

Or is it even worthless to talk about the other aspects of marketing beyond advertising?

Ram