Before you layout a circuit, it's generally a good idea to understand what is happening in your schematic. And before you lay out a schematic, it's generally a good idea to understand what is happening in your block diagram.
"This book is a bit technical. If you are a beginner, it's okay that you don't understand everything that follows -- your first project will still be successful. Try to pick up as much as you can, and ask questions in the forums!"
9. Piezo Buzzer
When crystals are exposed to electric fields, they flex and deform.
This artistic interpretation of crystalline deformation is from an article on piezoelectrics at AllAboutCircuits.com
By attaching the crystal to a substance that doesn't flex in the presence of electric fields, differential stresses can be used to cause air molecules to vibrate at audible frequencies.
This animation of a piezoelectric speaker is from an article on piezoelectrics from AllAboutCircuits.com
Dr. Bob's piezo-electric buzzer uses a DC blocking capacitor in line with a piezo-electric element to create an audio buzzer for our badge.