It's a little awkward, so we'll get straight to the point: This Friday we humbly ask you to defend Wikipedia's independence. We depend on donations averaging about $16.36, but 99% of our readers don't give. If everyone reading this gave $3, we could keep Wikipedia thriving for years to come. The price of your Friday coffee is all we need. When we made Wikipedia a non-profit, people warned us we'd regret it. But if Wikipedia became commercial, it would be a great loss to the world. Wikipedia is a place to learn, not a place for advertising. It unites all of us who love knowledge: contributors, readers and the donors who keep us thriving. The heart and soul of Wikipedia is a community of people working to bring you unlimited access to reliable, neutral information. Please take a minute to help us keep Wikipedia growing. Thank you.
An SSL certificate ensures all information transmitted to and from your website is protected from third parties attempting to access it. It is important because browsers, like Google Chrome, mark pages without https and the green padlock in the address bar as not secure. This can have a negative effect on the trustworthiness of your website. Pages that are protected with SSL receive better search engine rankings, and are more likely to be trusted by visitors.
A domain must be unique (for example there can only be one single Yahoo.com) and must be registered with a domain registrar (ie. NameCheap); while for sub domains, users can freely add it on top of the existing domain as long as their web host provide the service. Some would say sub-domains are the ‘third level’ domains in the sense that they are simply “sub folders” under the domain root directory, normally used to organize your website content in different languages or different categories.