How the Malicious Code Damage a Website and its Visitors?

Jang.com.pk and few other the Pakistani websites got marked as the malicious websites by Google. To actually understand on how all this happened, and what ways are there to  the avoid such instances, let me briefly discuss it for you guys.Website example.com.pk a very well known website of the Pakistan and it is known for the quality of content. But unfortunately, they didn’t do any security