Marketing is promoting a service like an exchange.
It can be even more than that.  It can be about selling a brand, or even a lifestyle.
Yes I agree.  Self publishing of a book is a type of marketing.
You're quite right, especially if part of selling the book you're trying to get a message through, or starting to get the word out of you as an author.
Some of the best author solutions are Palibrio and Booktango.