Google Adsense is a CPC (cost-per-click) advertising program that allows publishers (anyone wanting to put ads on their websites) to insert a small amount of HTML into their sites and have ads appear that are targeted and relevant to the content of the site. This means that your main task will be to provide as many clicks to those ads as possible. Adsense is about the easiest way for bloggers or webmasters to start making money with their sites.
The best part of Google Adsense is that it is free to use but it has some Criteria to Get Approved. The only thing to consider is the content should be original and not copied also free from Copyright violation.