How to insert jQuery code? Uncaught ReferenceError: $ is not defined in view razor code

You need to include JQuery before you actually use it.

A common way to achieve this is in your master layout include your require scripts in the head. Or place an optional section (head) where you can conditionally include scripts

First create a required bundle for your jquery scripts you want on every page:

public static void RegisterBundles(BundleCollection bundles)
{
    bundles.Add(new ScriptBundle("~/js/required").Include(
        "~/Scripts/jquery-2.0.2.js"));

    //other bundles
}

Then create a site template:

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8" />
    <title>Title</title>
    @Styles.Render("~/css/required")
    @RenderSection("head", false) //For css on a page by page basis
</head>
<body>
    @RenderBody()
    @Scripts.Render("~/js/required") //Here add your jquery include
    @RenderSection("scripts", false) //Here you add scripts at the bottom of the page
</body>
</html>

Then use this razor file as the base layout for all other derived razor views like this:

@{
    ViewBag.Layout = "~/Views/Shared/_MasterLayout.cshtml";
}

@section head {
     //Any css you want to add
}

<p>Some html content</p>

@section scripts {
    //scripts you want to include at the bottom on a page by page basis
}

Move the following lines of code to the top of your _Layout.cshtml view inside of the body tag. Then the jQuery scripts will load first.

<body>
    @Scripts.Render("~/bundles/jquery")
    @Scripts.Render("~/bundles/bootstrap")
    @RenderSection("scripts", required: false)

Your Script is called before the jquery is even loaded so it doesn't know what $ means. Try having the jquery scripts loaded in the head section of your layout file.