The object touched becomes invisible, vanishing from sight, even from darkvision. Neither you nor your allies can see the subject, unless you can normally see invisible things or you employ magic to do so. Using magic to see the object is difficult, as the object becomes immune to divination spells such as see invisibility or true seeing.
Light never becomes invisible, although a source of light can become so (thus, the effect is that of a light with no visible source). The subject is not magically silenced, and certain other conditions can render the recipient detectable (such as falling onto a hard surface).
You must designate a piece of glass, no smaller than 1 inch in diameter, through which a person can view the object. The object and piece of glass must remain within 30 feet if one another or the spell will end. Wizards sometimes use this spell to hide their spellbooks from all detection; they keep the viewing glass so they may still find and read the book.