Tub tile caulk is a sealant specifically designed for use in bathrooms. It is designed to create a waterproof seal between the tub and tile, preventing water from seeping underneath and causing damage. Tub tile caulk comes in a variety of formulations, each with its own benefits. Some caulk is flexible, allowing it to move with the tub and tile as they expand and contract due to temperature changes. Others are formulated to resist mildew and mold growth, making them ideal for use in humid environments.