Next -It passes management to a consecutive matching route. OR a operate to pass management to 1 of the following route handlers.
The argument could also be omitted, however, is beneficial in cases wherever you have got a series of handlers and you’d wish to pass management to 1 of the following route handlers, and skip this one.
app.get(‘/user details/:id?’, function(req, res, next));
Req and Res: It represents the request and response objects
Next: It passes management to a consecutive matching route.