Azure Key Vault is a cloud-based service that securely stores and manages cryptographic keys, secrets, and certificates. It offers two service tiers: Standard Tier with software-protected keys and Premium Tier with HSM-protected keys for enhanced security. The pricing structure varies between the two tiers, with the Premium tier being more expensive due to the additional security features. Key Vault provides a comprehensive solution for secrets management, integrating seamlessly with other Azure services, but may lack certain functionalities compared to alternative solutions like Infisical. It follows a pay-as-you-go model with no upfront costs and can be used with applications hosted anywhere, not just in Azure.