Occasionally I read some article that utterly confuses online publishing with e-publishing. The only direct relationship between the two is that the Internet is often used to promote or deliver documents produced with e-publishing. On the other hand, online publishing is all about the document or book being freely available online. I suppose you could argue with the "free" part, that's just my definition, but online publishing is tied 100% to viewing documents in your browser. E-publishing includes CD collections delivered by mail, documents sent as e-mail attachments, and frequently, DRM (Digital Rights Management).
So, who cares about putting labels on things? I do, it's impossible to have an intelligent discussion without a common vocabulary. I've engaged in both online publishing and e-publishing over the years, and though I try to use the two in a complimentary manner, many publishers go whole hog on one or the other. I've been publishing online since 1995, and I actually started with the hopes of building a readership for fiction I'd been writing. As it became clear that the fiction wasn't going to pay the bills, I started paying attention to the traffic my site was getting for some off-the-top-of-my-head technical support documents I'd written. For the next ten years I continued publishing online without directly earning a dime. Was it selfless altruism?
Nope, it was good marketing. I didn't like the online revenue models that existed at the time (mainly banner ads) and didn't want to junk up my site for pennies a day, so I stuck with conventional publishing as a trade author and as a self publisher, and used my online publishing to promote my books. It wasn't an exact match since I did quite a bit of writing about subjects I never authored a book about, but writing gets to be a habit and you never know what might develop. Since that time, contextual advertising programs such as Google Adsense have given publishers a civilized way to earn some money from online publishing, but it remains a secondary objective for my publishing business.
E-publishing held a serious attraction for me early on because it promised to level the field for small publishers. E-publishing almost entirely eliminates production and inventory costs, though my first CD burner, purchased back in the early 90's, cost me almost $2,000. Unfortunately, the entire e-publishing industry based on CD media was quickly overwhelmed with shovelware, CD's stuffed with whatever royalty free garbage the publisher could find. In the end, publishing on CD (excluding software) was largely given over to professional subscriptions and niche products.
A few years later, the Internet exploded out of the academic and military environments and into the home, and e-publishing was given a new life. I attended an e-book conference put on by the National Institute of Standards in 2000, certain that this would be the new direction for my publishing business. After three days in D.C., it became clear that the industry leaders were no closer to agreeing on standards than our political leaders were to agreeing on policy, and I put e-publishing on the back burner. I still remember that one of the big names at the conference was an e-publisher named "MightyWords" who focused on mid-length documents for professionals and businesses. A year or so later they were purchased by Barnes&Noble.com. A year or so after that, Barnes&Noble.com got out of the e-publishing business entirely, and even closed their e-book store.
I finally started e-publishing for profit last year when I signed up with Lightning Source to distribute e-book versions of my print books. Since that time, it's reliably added about $500 / month to the bottom line, and given overseas customers an inexpensive way to purchase my books. I haven't seen any year-over-year increase in my e-publishing sales, which take as an indication that the e-book industry is growing due to title growth, rather than unit growth per title.