Each site has several icons in several formats. Make sure to include where you found the icon, the exact url and format.
Alternatively when asking about the site type, include which of the url fields are at play:
- favicon_url
- high_resolution_icon_url
- icon_url
Note that high_resolution_icon_url got added in the 2.1 version.
If your question is about UI aspects, consider the tag logo as well.