A domain is the URL, or the website address, where your customers go to find your store online. You manage your domain settings for your online store on the Domains page in your Shopify admin. If you use the wholesale channel, then you manage the domain settings for your wholesale store on the Domains page in that channel.
Your primary domain is the domain that customers see when they visit your online store. By default, your primary domain is your myshopify domain, which looks like
your-store-name.myshopify.com. You use your myshopify domain to log in to your store and identify your account when you contact Shopify Support.