A domain name can include up to 63 characters. You can use numbers, letters, and dashes in your domain but the domain cannot start or end with a hyphen. Domains also cannot contain spaces. Domain names are not case sensitive, so you can spell -- and advertise -- your domain in UPPERCASE, lower case, or BoTh cAseS for your email and website address. Special characters such as the underscore "_", the exclamation point "!", and the "@" sign are not permitted. Many people use variations of their domain name to maximize traffic to their site.