Prop - digital backgrounds. i.e. placing subject inside of or in front of a digital image. This is done taking the original subjects photo & editing it within Photoshop & adding to the digital prop.
Kathleen,
It's always better for most folk to do it the way you want it at the time of a shoot. However, many times clients have little critical response to a picture of themselves transported into in the redwoods, delicately lit with filtered light as dawn breaks. If the picture is flattering then they will likely be happy. Of course, this does not alter the kitsch-gimmicky quality of what the photographer delivered.
To get an Irish women in front of a castle, do that and it will be satisfying. Think a composite will suffice and you will invest in a lot of technical challenge and it may not work anyway. However, one still should learn to do composting as one may want to repair an image that is missing an important feature present in another picture.
I had occasion to rescue pictures taken by another photographer of a family and their high bred pooch by their brand new red enamel letter "O"14 foot sculpture. It was for a christmas greetings card. The lady suffered from a condition where almost always her eyes are completely shut, especially if you wanted them open! The dog likes to look away and the husband is always perfect. I simply cloned the ladies open eyes from a photograph where she was fine but the dog was off doing his thing. The eyes needed to be at a different angle so I altered that with the transform function (Selected that area, edit, Transform, free transform/distort/warp) and then it fitted perfectly. Well the ighting was different and when that was corrected it fused perfectly.
Such minor alterations should be in our capability "just in case". So it's very worthwhile to gain the skill to bring in objects to a new background or change backgrounds. Still, everything is best done right at the time of capture.
For my own artwork, however, I plan from the beginning to have a new background from before I've shot the first model. On the flip side, I may start with the background and then I have mapped out precisely where and how a person might be fitted in seamlessly. Since I'm imaging things that only exist in my head, I have an excuse for compositing. I still find it as frightening as it's wonderful! Just overlook one parameter and the thing can look fake!
You might share what about compositing appeals to you that you can't get from using a painted wall, a board, cloth or real life background.
Asher