Google AdSense program provides you reports which you can use for tracking the performance of your AdSense Ads. There are certain basic reports which are as such available on all AdSense accounts. These reports will show you the total number of page impressions, ad unit impressions, ad clicks, cost per thousand impressions (effective CPM), click through rate (CTR), and your earnings of course. You can view the reports for the date range of your choice. However, do not expect the report to be updated every second. Typically, the data is updated by Google AdSense program after every hour.
You can customize these reports for advanced performance tracking. Though simple customization of basic reports is useful too, it’s the ‘channels’ that really help in conducting a detailed performance analysis. Using channels you can get data broken down and presented in a number of different ways e.g. you could compare the performance of one set of pages against another, you could compare the performance of one ad format against another etc. There are various options available with channels and it’s just a matter of exploring them and using them to your benefit.
Besides viewing the reports online, you can even download your reports (in CSV format – comma separated values format). If you don’t want to login to your AdSense account very frequently, you can set up email-able reports which automatically get emailed to you or whoever you designate.