You can easily download and install apps on your Android Mobile phone that are not officially available in the Android Market (now Google Play) or have not been approved by Google yet.

The Android App developer will offer the app as an .apk file – think of this as the .exe installers that ship with Windows software – and you just need to open that file in your Android Phone to install the app.

However, there’s one change that you need to make to your Android phone before installing .apk files directly. Go to System Settings – > Applications and check “Unknown Sources” to allow install of non-Market applications on your Android phone.

Open Application Settings  Allow Apps from Unknown Sources