If you look around your house carefully, you’ll notice caulk everywhere. It’s especially common around bath tubs, sinks, and other wet areas. In these areas, caulk helps protect from water leakage. For instance, the caulk around the edge of your tub keeps water from seeping between your tub surround and the wall.
Over time, caulk can dry out and crack, so that it no longer protects against water damage. If you notice cracking caulk, scrape out the old stuff and recaulk the area, as needed.