The Clearlyexplained.com website does not collect private details while you browse the site. However, due to some advertising on the site those advertising agencies, like google adsense, may track you via 'web cookies' associated with serving those ads.
Typically those cookies don't know much. It can help to clear your cache in your browser every so often to reduce the amount of tracking websites engage in. Although you may need to log back into some pages you visit frequently.
If you send an email to clearlyexplained.com your email is stored here but is not compiled into database connected directly to the internet. Yes your email is stored but it is not sent to any other party or person unless required by law.
The privacy of following Twitter and Facebook clearlyexplained.com pages are covered by those organisations policies.