In mongoDB atlas, you have a connection string that looks like this:

mongodb+srv://username:<password>@clustername.je7f6.mongodb.net/myFirstDatabase?retryWrites=true&w=majority

My question is on that part after the cluster name .je7f6. I'm trying to get what this part of the connection string is called. What is it called? (Additionally: what is its purpose?). I'm asking because it's confusing to merge it with cluster name in the same variable when using a .env file for example. I've been searching online but can't seem to find anything on this yet.