OpenTelemetry is an open-source project that provides standardized APIs and libraries for collecting, transferring, and analyzing telemetry data. It helps to make systems more observable by providing a way to collect logs, metrics, and traces in a distributed system. Traces expose the entire journey of an action or request as it moves across all services in the system, while context propagation is used to send context from service to service to follow the execution flow. OpenTelemetry has several benefits, including vendor agnosticism, cross-platform support, automatic and manual instrumentation, clean architecture with separation of concerns, and production-ready version 1.0 released in March 2021. Instrumentation involves adding traces and spans code to an application, which can be done manually or using auto-instrumentation agents. OpenTelemetry is composed of API, SDK, and collectors, with the latter being optional but allowing for sending data to different backends without redeploying applications. AWS Distro for OpenTelemetry provides upstream-first, AWS-supported distribution of the project with enhancements such as SDKs for X-Ray trace format and context, and exporters to AWS services like CloudWatch and X-Ray. Enabling OpenTelemetry for a Lambda function is straightforward, involving adding an ARN, specifying environment variables, and configuring the layer.