Caulks and sealants are used to fill gaps and holes, like those found around doors, windows, pipe, and joints. Closing gaps helps keep out water and pests, reduces drafts and airflow, and provides a finished look. Caulk is used to fill gaps between joints and give a finished look. They're generally less flexible than sealants and are used where movement in the joint is limited. Sealants are elastic and stay flexible overtime, even when exposed to moisture and temperature changes. Apply caulks and sealants using a caulk gun or spatula, directly from a spray can, or from a roll.