How to get data from the client to the server (without url parameters) in Node.js?

Besides passing data trough the url parameters, how can I get data from, a form in the client index.html to my server.js file in Node.js?

I know how to get the data from the server to the client, but without using url parameters, I don't know how to do it the other way (client to server).

via Diogo Capela