Yes, you can start a sentence with "and." The belief that it is grammatically incorrect is a myth with no real basis in formal writing rules. Starting a sentence with "and" is often used for stylistic emphasis, to create a natural flow, or to add dramatic effect. Many modern grammar guides and style manuals accept and even encourage this usage when it enhances clarity or impact. However, it is important to ensure that the sentence beginning with "and" is a complete sentence with a subject and predicate, not a sentence fragment. Also, overusing it might make writing seem repetitive or informal, so it should be used thoughtfully, especially in formal contexts.