Google Ads (previously known as Google AdWords) is based on pay-per-click (PPC) advertising which means that you only pay Google when someone actually clicks your ad. When your ads are online and visible to users you don’t pay anything to Google. Your costs are determined by your maximum CPC, your daily budget and the number of people clicking your ads. On some days you might end up spending a bit more than your daily budget because there's the possibility to attract more traffic to your site. But these days are automatically balanced out by days when you spend less than your daily budget. At the end of the month, you'll never end up spending more than your monthly charging limit, which is your daily budget multiplied by the average number of days in a month (30,4). You can always log into your Cobiro account and easily adjust your settings including your budget or max. CPC from your Cobiro Dashboard.