A webpage can specify a small icon to represent itself. Opera will display this icon on tabs and bookmarks.
The standard method of doing this is to specify link rel="shortcut icon" in the page document. However, on some servers a file called favicon.ico is put in the root directory without a link from the document.
By default, Opera will display both types of icons.
Page icon settings
If you want to ignore all webpage icons, or to display only icons correctly linked from within documents, you can change the settings. Go toand choose the required settings in the "Page icon" field.