APIs (application programming interfaces) are sets of rules and protocols that enable communication and data exchange between different applications or systems. APIs can facilitate interoperability when extracting and pooling data among different CSPs (cloud service providers) by allowing standardized and secure access to the data sources and services offered by each CSP. APIs can also enable automation, scalability, and customization of cloud solutions. Reference: CompTIA Cloud Essentials+ CLO-002 Study Guide, page 163; CompTIA Cloud Essentials+ Certification Training, CertMaster Learn for Cloud Essentials+, Module 4: Management and Technical Operations, Lesson 4.3: DevOps in the Cloud, Topic 4.3.1: API Integration