Why use photogrammetry?
To capture real world objects with a camera and present them in a 3d environment as a model. It seems as though the most commonly used photogrammetry technique is used to capture organic elements like rock and dirt. With more precision and solid techniques you can obtain more detailed 3d objects like shoes, statues, and toys.
You might come to the realization pretty quickly after reading & watching the videos below that obtaining a digital 3d model from the real world is a very intriguing, great skill to start learning, especially while in its early adoption stage.