Cost-Per-Action (CPA) is a digital marketing model where advertisers pay for a specific action taken by a user, such as making a purchase, signing up for a newsletter, or downloading an app. This model allows businesses to focus on measurable results, ensuring they only pay when a desired action occurs, rather than for mere clicks or impressions. In CPA advertising, the cost is determined by the effectiveness of the campaign in driving these actions. Advertisers often use platforms like Google Ads or Facebook Ads to set up CPA campaigns, allowing them to track performance and optimize their strategies for better returns on investment.