dir

The dir global attribute is an enumerated attribute indicates the directionality of the element's text. It can have the following values:

ltr, which means left to right and is to be used for languages that are written from the left to the right (like English);
rtl, which means right to left and is to be used for languages that are written from the right to the left (like Arabic);
auto, which let the user agent decides. It uses a basic algorithm as it parses the characters inside the element until it finds a character with a strong directionality, then apply that directionality to the whole element.

Usage notes

This attribute is mandatory for the <bdo> element where it has a different semantic meaning.

This attribute is not inherited by the <bdi> element. If not set, its value is auto.
This attribute can be overridden by the CSS properties direction and unicode-bidi, if a CSS page is active and the element supports these properties.
As the directionality of the text is semantically related to its content and not to its presentation, it is recommended that web developers use this attribute instead of the related CSS properties when possible. That way, the text will display correctly even on a browser that doesn't support CSS or has the CSS deactivated.
The auto value should be used for data with an unknown directionality, like data coming from user input, eventually stored in a database.

Specifications

Specification	Status	Comment
WHATWG HTML Living Standard The definition of 'dir' in that specification.	Living Standard	No change from latest snapshot, HTML5.1
HTML5.1 The definition of 'dir' in that specification.	Working Draft	Snapshot of WHATWG HTML Living Standard, no change from HTML5
HTML5 The definition of 'dir' in that specification.	Recommendation	Snapshot of WHATWG HTML Living Standard, from HTML 4.01 Specification it added the `auto` value, and is now a true global attribute.
HTML 4.01 Specification The definition of 'dir' in that specification.	Recommendation	Supported on all elements but `<applet>`, `<base>`, `<basefont>`, `<bdo>`, `<br>`, `<frame>`, `<frameset>`, `<iframe>`, `<param>`, and `<script>`.

Feature	Chrome	Firefox (Gecko)	Internet Explorer	Opera	Safari
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)

Feature	Android	Chrome for Android	Firefox Mobile (Gecko)	IE Mobile	Opera Mobile	Safari Mobile
Basic support	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)	(Yes)