The unicode-bidi property is another one
of those properties that's very hard for people to understand. The
"bidi" in "unicode-bidi" stands for "bidirectional" or "bidirectional
algorithm". This property adds (or "opens") an additional level of
embedding with respect to the bidirectional algorithm.
This property is used when you want to control the direction of your text (either
"right-to-left" or "left-to-right"). Basically the
only time you would ever need this property is
when you would like your text to read from "right-to-left" (for Asian
characters for instance). If you want your text to read from
"right-to-left" you must set this property to bidi-override. The
bidi-override value allows you to control the
direction of text in a block or
inline-level element using the direction
property. Or you can set this property's value to
embed if you want to control the direction of
text in an inline-level element only. Giving it a value of normal
does not allow your text to be displayed in a different direction (in
other words, it does not open up an additional level of embedding with
respect to the bidirectional algorithm).
Read
an official description of the unicode-bidi property from the W3C