CPA (Cost-Per-Action) is a digital advertising pricing model where the advertiser pays for a specified action linked to the advertisement. This action could be a sale, a click, form submission (e.g., contact request, newsletter sign up, registration, etc.), or any other action defined by the advertiser. CPA is often used when the advertiser wants to drive a specific customer action beyond a simple click, such as making a purchase or signing up for a service. This model allows advertisers to pay only for actions that contribute to their ultimate goal, making it a cost-effective approach to online advertising, especially when tracking and measuring these actions is feasible.