Nintendo DSi Browser
The Nintendo DSi Browser is a free-to-download web browser app available to owners of both the Nintendo DSi and the DSi XL. It is similar to the original Nintendo DS Browser, which was developed on a game card for the DS and DS Lite. Unlike the DS Browser, the DSi Browser is free of cost and requires no additional hardware; the DS Browser also required a memory expansion pack to work properly. This browser was available at launch, and is preloaded onto DSi XL units.
Improvements on DS Browser
The Nintendo DSi Browser is built upon the Opera 9.5 web browser, and utilizes the Opera Presto 2.1 engine. Built to run better than the DS Browser and running with more RAM available thanks to the DSi's improved hardware, the DSi Browser features advanced capabilities compared to its predecessor. These includes support for HTML5 canvas objects, support for CSS opacity and several text-character sets.
Adobe Flash
One element sorely lacking in the DSi Browser is support for Adobe's Flash software and Flash objects. Without this support, any Web page making use of Flash will never load completely. Large blank spaces where Flash objects were originally placed make it painfully clear exactly how little the DSi Browser supports Flash. As more and more websites include Flash content, the scope of the DSi Browser's capability continues to narrow.
YouTube
YouTube makes liberal use of Flash. Flash is the primary program used to embed video files into the Web pages. Since the DSi Browser has no Flash support, YouTube cannot be fully functional. You can visit the YouTube website, view messages and comments, and look up videos. But don't expect to watch any of them: all that you will see is a blank square. As of September 2011, the DSi Browser features no Flash support and there is no announcement to upgrade it with Flash.