Hello everyone, I'm an optometry student who is currently doing Optics 1, and I have a general question about focal points. I can do the math regarding F1, F2, and the nodal ray, and I am decent at drawing the ray traces, but I would like to know more about the actual real world applications and the big picture regarding these points. Can someone possibly tell me what the focal points are in real life? For example, when one sits with their face inside of the focal point of a concave mirror, one gets a magnified image of the face. This describes how a make-up mirror works. However, what I want to know is what does that actually mean? I feel like it has never been explained, and unlike many in my school, I didn't take any basic optics before coming into the program. Does this mean that for every lens or mirror, there is one spot where the image will be the best? When I take a pair of plus lens glasses and move them in front of my face, there is one spot where the glasses will be most clear, which is the focal point, but I just want to have a more clear understanding of what that actually means. Thanks for your time.