Domain Name or URL: your website name, e.g. www.yourwebsitename.com. This is an address for people to find you on the Internet.
Hosting, Website Hosting:
Physical hard drives hold the code for your website. These can be anywhere in the world and they are owned/run by the hosting company.
SEO: Search Engine Optimization. Undertaking certain strategies to improve the ranking of a website in a Google search, e.g.