  A good chunk of the introduction to this article made me cringe, actually.  There are way too many parentheses and comma, and at times it seems like there is a stretch for more wiki-links.  I tried re-writing a sentence and I could barley understand what its purpose was.  Below is a new version of the introduction that I think is more clear and still contains the relevant information for someone looking for more information.  I'll wait for comments before putting it on the main page.   A container or wrapper format is a meta-file format whose specification describes how data  and meta-data is stored (not coded).  A program able to identify and open a container file might not be able to decode the contained data.  This can be caused by  the program lacks the required decoding algorithm or the meta-data does not provide enough information.  By definition, a container format could wrap any kind of data.  Though there are a few examples of such file formats (e.g. Microsoft Windows's DLL files), most container formats are specialized for the specific requirements of the data.   For example, a popular family of containers is found among multimedia file formats.  Since audio and video streams can be coded and decoded with many different algorithms, a container format can be used to provide a single file to the user.     