Automatic CPC Bidding
You can choose automatic bidding and manual bidding. With automatic bidding, Google chooses a bid amount that falls within your budget. Be careful not to overestimate your daily budget, because it can quickly go south! Automatic bidding is useful if you haven't mastered the AdWords system yet. With manual bidding, however, you can achieve better returns.
Manual CPC Bidding
With manual bidding you get to choose the bid amounts by yourself. The advantage is that you have full control over the amount you offer for a click. Manual bidding is advisable if, for example, you have more money for one word than for another word. With automatic bidding you don't get to control this.
Maximum CPC Bidding
Google AdWords can give you a maximum of the cost of a click, which is the maximum CPC bid (Max CPC). This is the highest amount that the advertiser is willing to pay for a click. Sometimes the CPC pricing model also mentions pay per click (PPC, Pay-per-click).