var express $=$ require$(\text{'}$express$\text{'})$;

var app $=$ expre$$s$\text{'}()$;

app.get$(\text{'}/\text{'},$ function $($req$,$ res$)\{$

res.sendFile$(\_$dirname $+"/$I$+$ "file$\_$name.html$")$;

$\})$

In the above code segment, the app.get$(\text{'}/\text{'},$ function $($req$,$ res$)$ function will be called when we send

a request for the $/$contactUs$.$html page

a request for the home page or index page of a website, for example, when we type the website address in our browser and hit enter.

a request for the $/$aboutUs$.$html page

a request for the$/$home$.$html page