Advertorials are ads designed to look like articles and are usually published in papers and magazines. Those of you who subscribe to Realtor Magazine you will notice some of the ads follow this technique. All of them are ran by two people using different names for the project, and for the author by the way.
National magazines and papers also known to have such ads because some of the companies that advertise in them tend to use experienced copywriters. You may see a page long ad in USA Today that looks like an exclusive breakthrough product the paper is writing about.

The idea behind them is that when you, the prospect, go down to a newsstand or a bookstore to buy a magazine or a newspaper; chances are you are interested in the content of the paper or magazine and not to look at the ads.
So if you design your ad using the same layout and concept of an article and the prospect starts reading it, he will be too drawn into it and by the time he realize it is an ad, he would have already been sold on your services.
Others are not that cynical and use the same format because of it is powerful and increases readership. There are many ways to base your services selling on, you can base it on price, type of service or specialty, on uniqueness and so forth. But regardless of how you plan on selling, you must deliver your message to the prospect or he will not act.
An advertorial is basically a sales letter formatted as an article, contains all the concepts and techniques of a regular sales letter such as an irresistible offer and a powerful call to action. You do not really have to run them in national magazines and newspapers do you? Absolutely not. That would be too expensive for our type of prospects, but there are other ways to use these concepts.
One effective way to use this concept is when mailing out a professional looking sales letter or an over sized post card.
An over sized post card can hold about 2 page long sales letter. Due to the size and nature of the content, prospects tend to start reading to see what it is all about and you have accomplished your objective. Imagine getting a 6×11 yellow post card with huge eye catching and interesting headline and article format content. Would you not in the least be interested in reading some of it to see what it is all about? compare that to a 4×6 or 6×8 post card with a pretty picture of a house.
The main purpose of any marketing technique is to first and foremost get the prospect to look at your ad. The second most important technique is to get them to act!
Advertorial formats offer you the ability to draw their attention, then it is up to your sales letter to do the job of selling them on doing business with you.