CSS properties are characteristics of an element in a markup language (HTML, SVG, XML, and so on) that control their style and/or presentation. These characteristics are part of a constantly evolving standard from the W3C.
A basic example of a CSS property is border-radius:
input {
border-radius: 100px;
}There is an incredible number of CSS properties, and learning them all is virtually impossible. Adding more into this mix, there are CSS properties that need to be vendor prefixed (-webkit-, -moz-, -ms-, and so on), making this equation even more complex.
Vendor prefixes are short pieces of CSS that are added to the beginning of the CSS property (and sometimes CSS values too). These pieces of code are directly related to either the company that makes the browser (the "vendor") or to the CSS engine of the browser.
There are four major CSS prefixes: -webkit-, -moz-, -ms- and -o-. They are explained here: