Think of it as "document root " in apache/nginx configuration where we define the path of our code and where exactly our code is residing.
Think of it as configuration files in “sites-enabled” in nginx with all the required flags like.
- headers information etc
So the document root is siting there idle until/unless we don’t have any request on our nginx configuration asking about our application.
Same goes with Lambda and Api-gateway as well, you don’t get your lambda code running until it’s triggered by Api-gateway (or from some other services)