Vocal cords are two small bands of tissue stretched across your voice box (called the larynx) that vibrate to create sound when you speak, sing, or make any vocal noise. They work like the strings on a guitar: when air from your lungs passes through them, they vibrate rapidly, and those vibrations become your voice.

When you whisper, your vocal cords barely touch. When you speak normally, they come together and vibrate hundreds of times per second. When you sing a high note, they stretch tight and thin, vibrating even faster. For a low note, they relax and thicken, vibrating more slowly. Professional singers train for years to control their vocal cords with incredible precision.

Despite their name, vocal cords aren't actually cords or strings. They're folds of tissue, which is why doctors sometimes call them vocal folds. When you have laryngitis and lose your voice, it's because your vocal cords have become swollen and inflamed, which prevents them from vibrating properly. That's why resting your voice helps: you're giving those delicate tissues time to heal so they can vibrate smoothly again.