Good evening, M. Carreira,
The _Layout.cshtml file is the default Layout for your views. When you create a project in Visual Studio as Asp.Net MVC, it automatically creates this file. It contains the navigation bar that is at the top of the page, with a few links like, Home, About and Contact the footer as well.
In order for all of your Views to inherit this layout contained in _Layout.cshtml automatically, you should check that the ViewStart.cshtml which is within the Views folder of your project) looks like this:
@{
Layout = "~/Views/Shared/_Layout.cshtml";
}
If it is, everything in _Layout.cshtml will apply to all your views, without having to repeat code page by page;
If you want to change the footer or top menu, just change the _Layout.cshtml file that all the changes will be applied to all your Views, including your contact page.
If you have any difficulty, talk to me: D