What is this commercial photography thing anyway?
The very simplest way of putting it is, it’s photography for money, where the final images will be used to sell a product or service; as opposed to recreational or hobbyist photography that’s purely for enjoyment.
If the image will not end up being in an "advert" of some form, it's not commercial.
There are basically two branches to commercial photography, assignment photography and stock photography. Again, there is a very simple way of distinguishing these. With stock photography you have an idea, that you execute at your own cost and then subsequently try to license the images to make a profit. For assignment photography a specific brief exists and the photographer is hired to create an image/images to match that brief. The photographer executes the idea at the clients expense.
‘You make the image and then try to “sell” it’ vs ‘you “sell” the image and then try to make it’.
You’ll notice that sell is in quotes, that’s because commercial photographers typically don’t sell their images, they license them for use. A license basically grants a party (client) rights to use, within restrictions specified as part of the license, the intellectual property of a photographer or photography company.
Commercial images typically have a more polished look to them and are held to higher standards than most residential (family portraits, wedding photography) images.