Tapit recommends using the following URL format for linking to an App in the Android Market:
In this case, the <packagename> parameter is the target application's fully qualified package name, as declared in the package attribute of the manifest element in the application's manifest file. As an example, if an advertiser wanted to drive users to Tapit's Lunar Lander sample app they would use the following URL:
Tapit recommends using the above URL because we have found that routing users to the "Details" page of an app has the best results for driving app downloads. Taking users to this specific page allows them to easily install the app with the fewest number of clicks. The Android Market will always display the "Details" page for the latest version of the application.
If you are linking to an Android App that is not in the Android Market, we do allow you to provide the URL that does begin with http:// .
Note: You can find additional URL's which will allow you to link to your App in the Android Market at the Publishing Your Android Applications page.