Twitter was an all-English network until April 2008, when the platform added support for Japanese.
Spanish and French translations became available in November 2009, and last month we highlighted the addition of Brazilian Portuguese, which brought the total number of languages available (including English) to ten.
Now, with newly-added support for Dutch and Indonesian, that figure is up to 12.
Says Twitter on their official blog:
Dutch and Indonesian were the first languages to be fully translated by community volunteers using our Translation Center that opened earlier in the year. Volunteers translate twitter.com, support pages, desktop and mobile applications — everything except the Tweets. Then, a select group of the most active translators work closely with the team at Twitter to maintain localized versions of the service.
Twitter is working on adding support for Filipino and Malay in the next update.
To change your language, visit the Account tab of your Twitter profile settings on Twitter.com and make your selection from the Language drop-down menu.
(Source: Twitter blog.)