HTTP
Hyper Text Transfer Protocol
Your web browser (typically Internet Explorer or Mozilla Firefox) asks the central US database (which holds all domains) to locate a domain, e.g. domain.co.uk.
The database then tells your browser which domain name server (DNS) holds the relevant information for that particular domain, in this case, domain.co.uk.
Your browser then contacts the DNS, which returns the IP address for domain.co.uk, which will be a series of numbers looking something like 255.134.323.43, identifying the location of the web server that stores your site's internet files.
The browser then requests the required file or files from the server, and the server delivers it to your browser for you to view as a page.
SMTP
Simple Mail Transfer Protocol
Similar to HTTP, when you send an email to for example someone@domain.com, the central DNS server will transfer your message to the correct server where your email for the domain name will be handled.
Differing from HTTP, SMTP works via a separate port on the web server so the two requests are kept separate and depending on what email software is handling mail, messages are then stored in the appropriate folder for collection later.
