How to include jQuery in ASP.Net project?

You can download the latest version of jQuery and then include it in your page with a standard HTML script tag or can use CDNs available from Google, Microsoft and give the CDN URL in ASPX page.

Download jQuery

You can download latest version from.... Download jQuery and include the script file directly in your asp.net master page .

 
<script type="text/javascript" src="/scripts/jquery.min.js"></script>

Using Content Delivery Network

Alternatively you can use a content delivery network (CDN) to deliver your jQuery. Both Google and Microsoft host jQuery. Using a content delivery network (CDN) can help improve performance of your jQuery (and website as a whole).

Google CDN

 
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>

Microsoft CDN

 
<head>
<script src="https://ajax.aspnetcdn.com/ajax/jQuery/jquery-3.3.1.min.js"></script>
</head>

Next : Need to add jQuery file in both Master and Content page?