Ruby characters (ルビ, Rubi) are small, annotative glosses that can be placed above or to the right of a Chinese character when writing languages with logographic characters such as Chinese or Japanese to show the pronunciation. Typically called just ruby or rubi, such annotations are used as pronunciation guides for characters that are likely to be unfamiliar to the reader.
The first parameter is the base (the lower part) and the second is the Ruby text (the smaller part on top or in parentheses).
|style=can be used for adding more style to this text. For specifically CSS styles to control Ruby text layout, see Ruby Formatting Properties at W3C website.
The manner in which the Ruby characters are displayed is dependent upon the browser. For browser support, see Ruby annotation at Can I use.
If you see , then your browser supports Ruby.
If you see Base(top), then your browser does not support Ruby.