What is practical purpose for bidirectional override "bdo"?

Question

Before coming here, I tried myself by googling. After I read these two links

http://www.w3schools.com/tags/tag_bdo.asp

http://www.w3schools.com/tags/tryit.asp?filename=tryhtml_bdo

I still don't understand clearly what is the practical purpose?

Thanks in advance for those who shed some light on this.

Answer 1

Pretty striaghtforward. If you're writing a web page using a default language, such as English, that is rendered left-to-right, and you want to include a island of text in another language, such as a quote in Hebrew, that is rendered right-to-left you can use this tag to override the base direction in which the text is written onto the page in case the bi-directional algorithm is getting it wrong. You need to make sure that the font you're using supports the appropriate character set too, of course.

http://www.w3.org/TR/html40/struct/dirlang.html