There are, at least, two types of domains for SEO services which are the sub domain and the costume domain. Therefore, you need to choose either of them for the SEO services you use. You can ask your SEO services providers such as the provider you can visit on www.pagesatu.com to help you. But, first, it is better to understand the meaning of them. In the following, then, it will be discussed what a sub domain is.
A sub domain is a domain that is added to the primary domain which is usually called a top-level domain, a kind of website which is a lot larger than the sub one. For example, if you use a free blog service that gives you extensions like blogspot.com or wordpress.com, they will create your blog address, for example, to be yourname.blogspot.com. Indeed, blogspot.com itself is a domain. When the word your name is in front of it, it means he becomes part or sub of blogspot.com domain.