In CSS, the "font-family" property is used to specify the font used for text within an HTML element. It allows you to choose from a variety of different fonts that are available on the user's computer or device.

In CSS, the "background-color" property is used to set the background color of an HTML element. This property can be applied to a variety of elements, including the body, divs, headings, paragraphs, and more.

The <div> tag is an HTML element used to create a block-level container. It's used to group together HTML elements and apply CSS styles to them as a unit. The name "div" is short for "division," which reflects its purpose of dividing the content into logical sections.

The "text-align" property is a CSS property used to control the horizontal alignment of text within an element. You can apply the "text-align" property to any block-level element, such as headings, paragraphs, and divs. You can also apply the property to the body element to align all text on the page.

Font icons use a custom font that includes icons instead of letters. You can use CSS to apply the font to specific HTML elements and then use the corresponding icon codes to display the icons. Some popular font icon libraries are Font Awesome, Material Icons, and Ionicons.