Overview: Microsoft Sentinel is Microsoft's cloud hosted SIEM solution. It can take data from Azure, on-prem., and other cloud infrastructure such as AWS. Sentinel gathers data from various sources, and evaluates to generate alerts.
SIEM allows software products and services to bring security information/events into a management tool to provide real-time analysis of security from all applications and networks across the enterprise. SIEM stands for security, information, and event management and is commonly used by the COS (Security Operations Teams of a business), the SOC is often outsourced or partially outsourced to Service companies e.g. Avanade are good at this. Other SIEM products are: SolarWinds security and monitoring (great product), McAfee ESM, Rapid7, Splunk, and Datadog. There on installable and SaaS solutions but I prefer SaaS solution like Microsoft Sentinel. AWS and Google also provide SIEM services.
Microsoft Sentinel (previously called Azure Sentinel) is cloud-native and collects SIEM data from systems, applications and networking to provide an overview of the organizations security alerts, and allows identification for remediation. It accepts several common formats for capturing events and offers a REST - API. Sentinel also has a ton of native connectors.
"Microsoft Sentinel is a scalable, cloud-native, security information and event management (SIEM) and security orchestration, automation, and response (SOAR) solution." Microsoft Docs
