By default, Joomla imposes article text filtering on all user groups, which strips away certain HTML tags depending on your user privileges. To prevent this, you can configure the 'Filter Type' of your user groups to 'No Filtering' or your preferred filter groups.
This includes the following tags:
- 'applet', 'body', 'bgsound', 'base', 'basefont', 'embed', 'frame', 'frameset', 'head', 'html', 'id', 'iframe', 'ilayer', 'layer', 'link', 'meta', 'name', 'object', 'script', 'style', 'title', 'xml'.
You can configure Joomla from stripping away your HTML tags by configuring your user groups ‘Filter Type’ to ‘No Filtering’ or your preference for the respective Filter Groups.
You can do this by going to 'Global Configuration' and clicking on the 'Text Filters' tab.
For more information, please read Joomla’s official documentation on how to setup and configure your Article Filters; please see: http://docs.joomla.org/Help30:Site_Global_Configuration#Text_Filters