In App Store, all apps have to be artificially checked by reviewers before putting on the store. If the result of checked app reveals malicious, it then will be removed and disallowed. However, in Android market, instead of using a top-down approach to malware prevention, Android uses crowd sourcing which bases on user's rate and comments on apps. If enough users complain about an app which will be removed from the Market and also can remotely remove it from devices