Private-party ads are ones placed with no ongoing commercial interest in the outcome. In other words, multiple responses do not each generate potential revenue. Here are some examples:

• An individual selling their car.
• A business advertising a specific used car for sale.
• Looking for a lost relative.
• Looking for work.
• Offering a specific job position - one where a person is hired to perform a specific job for a salary. Note, this does NOT include work-at-home, MLM, or other such "business opportunity" positions. These are jobs where the direct employer taking out the ad pays the hired person a fee or salary.
• Listing a specific home for sale.

Commercial ads are ones that attempt to generate revenue on an ongoing or repeated basis. Commercial ads can be posted by individuals or businesses where each response has the potential to generate revenue for the ad owner. This can be from selling eBooks, Computers, Services, and more. Here are some examples:

• Any business advertising their service. For example, a car dealer stating they have a number of cars at great prices, just come to their store (or Web site). However, a car dealer could advertise a specific used car for sale as a private-party ad.
• A business advertising an individual product that they have multiple units in their inventory. If you are selling Sony VAIO R505G laptop computers and have 10 in stock, then an ad for this single item is commercial.
• Work-at-home, MLM, and other such business opportunities. Even if the service they are promoting (such as "get paid to read email") costs the responder nothing, the ad owner can be making revenue off of each person who signs up.