Your website's address on the internet that customers type into a browser, like your store name followed by .com or .sa.
A domain name is the easy address people use to reach your site instead of server numbers. You buy or renew it yearly from a domain registrar and choose an extension such as .com or a national one such as .sa or .ae. Some national extensions have their own registration requirements.
Your domain is part of your brand and customer trust. Your own domain looks more professional than a subdomain on someone else's platform and stays with you if you change hosting providers. It is also used for your company's official email.
Practical tip: register the domain in your own or your company's name, under an account you control, not the developer's or agency's. Turn on auto-renewal, because an expired domain can take down your site and email suddenly, and someone else may grab it.