You can use them or not. In MVC, global.asax calls RegisterBundles, where those bundles are defined. In RegisterBundles, you define which files are bundled. If you take out the call to RegisterBundles, they won't be used. I'm pretty sure it's similar in ASP.Net

>I read a couple of articles about bundles and some discussions on stackoverflow. Bundles are good but could be very confusing for a novice (and from some questions on stackoverlow even for experienced). I wish creators of VS would make the bundles work more intuitive; and maybe allow the developer to decide if he/she wants to use them and when.
>
>>Bundles are a good thing. In a web application, if you list each css file separately, each must be loaded separately. That means for each file, you have to contact the server, establish a connection, download the content, the disconnect. With a bundle, multiple files are automatically combined. So if you have three files in the bundle, the browser connects to the server one time, which speeds up page load.
>>
>>
>>>

>>> <webopt:BundleReference runat="server" Path="~/Content/css" />  
>>>

>>>
>>>This is how they (VS) load all CSS.
>>>Thank you.