I'm asking you to confirm that you're not an automated computer program being used by a spammer. If I didn't do this, a spammer's computer program might be able to use my Guest Book to send spam to me or on to others. This is annoying & wastes the time and efforts of all recipients. People are smarter than computers, so I'm asking you to enter the text you see in the image as a sort of Turing test because a computer program probably can't do it successfully. By entering the text correctly, you're helping my server confirm that you're a real human being, not a computer program, and that you may have valuable human input for me which I will want to receive.