Web design refers to the design of websites that are displayed on the internet. It usually refers to the user experience aspects of website development rather than software development.
SEO stands for “search engine optimization.” It is the process of getting traffic from the “free,” “organic,” “editorial” or “natural” search results on search engines.
Ecommerce refers to commercial transactions conducted online. This means that whenever you buy and sell something using the Internet, you’re involved in ecommerce.