Chemistry help??? i need somene to explain sumthing to me?

Before titration is complete, starch is not used because not all the Iodine in the solution had reacted with the sodium thiosulphate, the reason why we use starch to test is because after titration had reach its end-point, we need to know whether all the aqueous iodine had reacted with the sodium thiosulphate, thus starch is used to see whether there is any color change in the solution (remember that all sodium salt is soluble salt and using indicator is the only way to test for the end-point of reaction)