I deploy my backend in Azure web app by using the azure vscode extension. The OS is linux and I use express.js and node.js the question is what is the web server that I used for now?
I also have a question about my frontend that i deploy to Azure static web app by use CI/CD in github what is the OS that host my website and also is it have web server?

For backend I search about azure web app server but mostly it tell me that it’s IISnode which should be use on Window but i use linuxAzure app service System info