CPC stands for Cost Per Click, which is a metric used in online advertising to measure the cost an advertiser pays for each click on their advertisement. It is a pricing model commonly used in pay-per-click (PPC) campaigns, where advertisers only pay when a user clicks on their ad. The CPC is determined by factors such as the competitiveness of keywords, ad quality, and bidding strategies. It is an important metric for advertisers to track and optimize as it directly impacts the cost-effectiveness of their online advertising campaigns.