Instances of a person or persons writing blog entries about about the same (or very similar) topic.
Dumping whatever is in your brain into writing. A care-free, no questions asked, write it all down without analysing it description of whatever concept, idea or topic you are thinking about.
According to After the Deadline, it is a cliché.
A content management system (CMS) is a system providing a collection of procedures used to manage work flow in a collaborative environment.
The original purpose of the Featured Image was to serve as a page (or post) specific header in place of the general site header. So as well as being able to customise your site’s header on a site-wide basis, you could use the Featured Image to make you post or page unique.
Not all themes support this type of behaviour any more. The default themes that come with WordPress out of the box seem to have stopped supporting it in this way.
Theme and plugin developers also use it for other purposes in a different context.