Covalent bonds are like a hug between atoms. Atoms are like people and they have parts that are negatively charged (kind of like a frown) and other parts that are positively charged (kind of like a smile). When the frowns and smiles get close enough, they can hug each other and share each other's parts, which is called a covalent bond. With a covalent bond, atoms can stick together and make different types of molecules.