How to allow Android mobile phone to install third party apps

If you are Android mobile phone or any other android device owner then you might be installing apps from Android marketplace. But sometimes you won’t find your required app in the appstore and you need to install third party app in your android mobile phone .

So, to allow android mobile phone to install third party apps, do the following :
Go to Settings and then Applications :

 After clicking on the Applications ,just enable the Unknown sources ,as described in the screenshot below :

 

And now you can install third party android apps on your mobiles.