The only way to be sure you have it all correct in your head is to work with the text or instructor notes you are using and work problems. On this page we will stick to some basics. Images viewed in plane mirrors appear to be behind the mirror. This image is called a virtual image. The virtual image is the same distance behind the mirror as the real object is in front of the mirror.
Real images are ones where the light from the image really comes from the image.
Virtual images are ones where the light appears to come from somewhere other than the image. For spherically shaped mirrors the focus of the mirror is at one-half the distance to the center of curvature. Light rays from infinity are all reflected so as to pass through the focus. The magnification of a mirror is defined as the image height over the object height. The magnification is also the image distance over the object distance with a negative magnification indicating the image is inverted.