What does the classid in an <object> tag do?

I always see a classid i开发者_C百科n tags when I do static publishing using SWFObject, i.e.

<object classid="clsid:D27CDB6E-AE6D-11cf-96B8-444553540000"

What is this for?? Can I just drop it?

The classid is define as

value as set in the Windows Registry or a URL

I know Flash embeds can work without the classid attribute, but I wouldn't recommended it.

SWFObject will implement the standard Flash embed code, so I would leave it.