NOR gate

The way that HTML is organised is similar to the relationships of a family. In the previous episode we placed a paragraph element within a body element. When an element is placed inside another element it is called the child of that element. We can also say that the child element is nested inside of the parent element.
A paragraph element nested inside a body element.

                                                                              

In this example the <p> element is nested inside the <body> element. The <p> element is considered a child of the <body> element and the <body> element is considered the parent.
Since there can be multiple levels of nesting, this analogy can be extended to grandchildren, great-grandchildren and beyond. The relationship between elements and their ancestor and descendent elements is known as hierarchy.