JQuery, the very very basics - Lesson 3

Snail on with my learning and writing about the very very basic lessons on JQuery. In "modern" (DOM) web programming, web pages are made up of a hierarchy of elements. Manipulation of elements goes far beyond styling and positioning, it involves almost everything, adding / deleting content, appending and removing children elements, attaching itself to a new parent, cloning ... Everything is possible. The question is : How?