Short answer, No. But you probably want some a formal business structure for the protection it provides, and an LLC is by far one of the easiest to form.
So what are the benefits of an LLC? An LLC, or limited liability company, provides personal liability protection which means your personal finances are protected from the business. If your business is sued or has unpaid creditors, you won't be personally liable.
Having an LLC can also help you access funding as banks and investors may be weary of loaning money to a business without a formal business structure.