Marketing attribution, a crucial concept in today's digital landscape, involves identifying and assigning value to user actions that contribute to conversions, which is vital for calculating return on ad spend (ROAS). Various attribution models, such as first-touch, last-touch, and multi-touch, attempt to understand and credit different stages of the consumer journey, but they face challenges like data gaps, reliance on cookies, and privacy concerns. These issues can lead to inaccurate ROAS calculations, prompting businesses to consider building in-house solutions or adopting device identification methods to improve attribution accuracy. Accurate device identification can overcome obstacles posed by deleted cookies or anonymous browsing by linking user sessions across devices, though it requires careful consideration of data privacy compliance.