With automatic bidding, the AdWords system adjusts your bids automatically to earn the most clicks possible within your budget. It isn't possible to set a specific cost-per-click (CPC) bid. You can, however, set an upper limit on the CPC bids for your entire campaign. This is the CPC bid limit. Specify a bid limit of $0.50, for instance, and the AdWords system will never bid over $0.50 on your behalf for any single click.
If it's important for your business to control the cost of individual clicks on your ad, it's a good idea to specify a CPC bid limit. For example, if you sell a product that costs $5.00, you may wish to set a CPC bid limit of $5.00 so you never pay more than that for a click.
By setting a limit you have more control over your costs, but you also may restrict your ad position or the number of clicks your ads receive. If you choose not to set a click price limit, automatic bidding will function as it normally does, choosing whatever maximum CPC bids it determines will earn you the most clicks possible within your budget.
If you'd like to have even more control, and choose a maximum CPC bid for individual keywords or placements, you might be interested in manual bidding for clicks.
