Cross-device capping refers to the practice of limiting the number of times an advertisement is shown to a user across multiple devices. This ensures that the same ad is not repeatedly displayed to a single user on different devices, preventing ad fatigue and improving the overall user experience. Cross-device capping is an important strategy for advertisers to effectively manage their ad frequency and reach their target audience without overwhelming them with the same ad. By implementing cross-device capping, advertisers can optimize their ad campaigns and deliver a more seamless and personalized advertising experience for users.