A Survey of Advanced Retrieval Algorithms in Ad and Content Recommendation Systems: Mechanisms and Challenges
What are the primary algorithms used in ad recommendation systems?

Ad recommendation systems primarily use algorithms such as machine learning, inverted index data structure for efficient matching, age and gender targeting based on demographic information, re-targeting focusing on users who previously interacted with a site, keyword targeting using specific keywords from user queries or viewed content, and behavioral targeting tracking user activities and interests.
How do content recommendation systems enhance user experience?

Content recommendation systems enhance user experience by suggesting personalized content based on users' preferences, behavior, and past interactions2. These systems analyze user data, employing machine learning algorithms to anticipate user needs and deliver relevant recommendations. This tailored approach streamlines decision-making, increases user engagement, and fosters customer loyalty.
What role does the inverted index play in ad targeting?

The inverted index plays a crucial role in ad targeting by efficiently matching user profiles with relevant ads. It creates a data structure that maps content to keywords or attributes, allowing for fast and efficient retrieval operations. Ad targeting models use the inverted index to profile users based on their online activities and match those profiles against the index to find relevant ads. This enables the delivery of personalized advertisements to specific audiences, maximizing user engagement and conversion rates.