Read:08 | More CSS Layout

Textbook: Jon Duckett: HTML & CSS (HTML book: Chapters 15)

CSS | Layout

It’s best to use an HTML tag like <div> that allow you to lump other tages inside of it to work as a container that you can assign an id to and use in your CSS file to move around the page
HTML pages in browsers have a standard flow until you specify in a CSS file if you want relative, absolute or fixed positioning for your various elements
The float: property is great for putting things to the left or the right of other elements on the page (Note: these require a defined width)
Your website can have a fixed or a liquid (today we call this responsive) layout (meaning things on the page might change depending on the size of your browser window)
Grids are an ideal way to think about page design, specifically the 12 column model (Things like Bootstrap are built off of this.)
You can connect multiple CSS files to your HTML document, but be mindful of the order the links are listed in for rendering purposes

Great image reference to the Visual & Code/Result of utilizing the Grid Layout