By default Google has disabled installing apps from unknown sources on Android smart phones. Google lets you just install apps from Android Market(now known as Google Play store). When you download Android apps from other Android market or websites and trying to install the apps on your Android phone, such as Samsung, HTC, LG, Motorola, Lenovo, Huawei, Xiaomi, Sony, Google Nexus and many more, you will have to change the Android settings to allow apps from unknown sources to be installed on your mobile phone first. If you get an error message like below it means you have not allowed installation of non-Market apps on Android phone.
For security, your phone is set to block installation of applications not obtained from Android Market.
How to install Apps from unknown sources on Android phones?
Fortunately Google allows Android users to download and install apps from unknown sources or websites. To do that, simply follow the instruction below.
1. Open Settings on your Android phone.
If you are on Samsung Galaxy phones, you can find Settings from Apps, or press the Menu button on your phone to quickly launch Settings app.
2. Go to Security
Android system recommend you to download apps from Google Play (Android Market) so you can avoid potential risks of malware, spyware or viruses infected apps. Thus the installation of Android apps from unknown sources option is grouped into the Security settings on the phone. In this demo, we are using a Samsung galxaly phone to show you how to change Android setting to allow installation of third party apps. If you are using other Android phones, such as LG, Motorola, HTC, Lenovo, Nexus, Xiaomi, Huawei, you may find they differ in appearances.
3. Allow installation of apps from unknown sources on Android
Check “Unknown Sources” to allow app installation from sources other than Google Play or Android Market.
Now you can go to download Android apps from other trusted app downloading websites or platforms and install them on your Android phone. You can see this guide to download Android apps from third party app markets on to computer and install Android app from computer to mobile phone. You should have enough permission to install most Android apps in APK file formats now. Still some Android apps work for rooted Android phones. These apps require root user or admin user privileges, you need to root your Android phone to gain full permission on the phone before you can install and use these apps. This is a bit off topic, we will not going to discuss further in this article.