TOPIC 1: HTML Describes structure

Basically every type of document follows the same type of structure; whether it is a newspaper, insurance document, or anything in between, they all have the same elements. Headings, subheadings, lists, images, etc; they all provide structure to the document. HTML serves as this structure for web pages, made up of tabs to tell the browser something about the information that sits between opening and closing tags.

TOPIC 2: CSS In a nutshell

As the book states, “the key to understanding how CSS works is to imagine that there is an invisible box around every HTML element”. CSS governs how content of specified elements should be displayed, containing a selector and declaration. The declaration contains a property and value, specifying several properties, each separated by a semicolon.

TOPIC 3: Different types of selectors

There are many different types of CSS selectors that allow you to target different elements in an HTML document. Universal selectors apply to all the elements in the document.
Type selectors match element names and deals with the h1 through h6 headings.
Class selectors match the elements whose class attributes have the value that matches the one specified after the period.
Id selectors match elements that follow a pound symbol.
Child selectors match elements that are a direct child of another.
Descendant selectors match elements that are descendants of another specified element.
Adjacent sibling selectors match elements that are the next sibling of another,
And lastly general sibling selectors match elements that are the next sibling of another but do not have to be directly preceding them.