Iodine is commonly used as an indicator for the presence of starch. When iodine is added to a substance that contains starch, it will react with the starch to produce a characteristic deep blue or purple color. This color change indicates the presence of starch in the sample.
If the substance does not contain starch, the iodine will typically remain a yellow-brown color. Therefore, the primary information that the iodine indicator provides is whether starch is present in the tested substance.