Whether to use a subdomain vs. subdirectory model is a long-standing debate in the SEO community. Another reason why you might use a subdomain is to separate the ecommerce portion of your website from its main domain. A subdirectory (also called a subfolder) is a folder located within the main domain. Exploring the Subdomain vs. Subdirectory DebateThe topic of subdomain vs. subdirectory is hotly debated in the search community. Optimize Your Subdomains & Subdirectories for SEOThe choice between subdomains and subdirectories largely depends on reasons outside of SEO.