What is CSS3
CSS3 language development is developing towards modularity. The previous specification was too large and complex as a module, so it was broken down into smaller modules and more new modules were added. These modules include: box model, list module, hyperlink method, language module, background and border, text effects, multi-column layout, etc.
When writing CSS3 styles, different browsers may require different prefixes. It means that the CSS property or rule has not yet become part of the W3C standard and is a private property of the browser. Although newer versions of browsers currently do not require prefixes, prefixes are still indispensable for better forward compatibility.