If you have tried making close-up, or macro, pictures of small objects like wildflowers or stamps, you may have been frustrated that your subject was not centered in the picture as you expected. This probably happened because you used the optical, or traditional window, viewfinder to frame your composition. But this window "looks" at your subject from a slightly different position than your camera's lens does. When the subject is farther away, this doesn't matter in the final result. But when your subject is close, framing with the window viewfinder can result in part of your subject being cut off, like in the first image above.
To solve this problem, use the LCD screen on the back of your camera to compose your photo. Because the screen displays what the lens sees, your framing will be more accurate.
There are two exceptions to this advice. First, some compact (point & shoot) digital cameras have an electonic viewfinder (abbreviated EVF). This is a miniature LCD screen inside an eyepiece. It shows you what the lens sees so it is fine to use for your close-ups.
Second, if you are using a digital SLR (a camera with interchangeable lenses, such as a Canon Rebel or Nikon D40), its viewfinder also shows you what the lens sees. So you can compose your photo with confidence.