How do people put ads on their blog

Question

i have a blog in many blogs people have ads how is that they have ads

Answer 1

Use google's adsense service.It gives you ads based on your blog contents or for putting up a search based ad system.

If people click on those ads,you get paid...you just have to use the ad's code provided by adsense into your blogs' source code...

I have got $100 before and another is due in  a week...

Answer 2

you can get all the details if you join adsense or just view the details in adsense help..