People are different. Even twin brother is not exactly similar. This makes, when there are 100 people in one place, it means there will be 100 different people on that place. Since people are different, what they like to do is also different. There are a lot of different hobbies that people do. And if they love to write anything, they usually have a blog as a place to store all of their writings.
Blog is like a personal website for those who love to write and if you make a good blog, you will get a lot of visitors coming to your blog just to read what you have written. And you know since you can actually convert the traffic of your blog into cash, you can get a lot of money when your blog is visited by a lot of people. This is actually something new because, just by copying and paste some code on the blog, everyone who visit your blog for more than ten seconds can be converted into some cash that will be paid to you.
You are actually putting some advertisement to your blog and, unlike the other program which requires the visitor to click on the advertisement, this program does not. Just by visiting the blog for certain time, and you as the owner can get the cash.