Human Capital Management (HCM) integration involves connecting HCM systems with other applications, often through APIs, to automate and streamline HR processes, which helps reduce manual work and errors while enhancing productivity and data accuracy. The integration allows organizations to automate user provisioning, manage documents, send gifts for work anniversaries, and gather compensation data seamlessly, improving the overall employee experience and ensuring compliance with labor regulations. However, challenges such as complexity, cost, data security, and system compatibility need to be addressed. Best practices include documenting integration builds, prioritizing integration requests based on specific criteria, and performing extensive integration tests. Platforms like Merge offer unified API solutions to facilitate and scale HCM integrations efficiently without heavily relying on in-house engineering resources.