Datadog is monitoring software - developers use it to get operational visibility (what’s broken? What’s taking too long?) into their servers and applications.
As applications and infrastructure have gotten more complex, developers need to know what’s going on under the hood so they can pre-empt and troubleshoot
Datadog provides a product and series of SDKs (little code libraries) that let you instrument your application, record your metrics, and analyze them visually
Generally, the Datadog platform has 4 major components: server monitoring, application monitoring, logs, and Other Stuff™
The New York based (surprisingly enough) company IPOd back in 2019, and is worth $23B (!) at the time of writing. So they’re definitely onto something.