To use jQuery, you need to include it on the pages where you wish to take advantage of it. You can do this by downloading jQuery from their website at jQuery.com. There is usually a choice between a Production (compressed) version and a Development (uncompressed) version - for learning, we recommend the Development version.
A part of your page should now look something like this:
You can use jQuery from a CDN just like you would do with the downloaded version, only the URL changes. For instance, to include jQuery 3.3.1 from Google, you would write the following:
I suggest that you use this approach, unless you have a specific reason for hosting jQuery yourself. Here is a link to the jQuery CDN information from Google:
Here's the information about using jQuery from a CDN from the official jQuery website:
Using jQuery can be accomplished by downloading the library or adding a reference to it on one of the many CDNs. Either way, you will usually get the choice between an uncompressed developer version and a compressed production version. For development and testing, use the uncompressed version to get more precise errors and understanding of the library. For production, you should use the compressed version to save bandwidth for your end-users, which will also result in faster load times for your website.
As soon as you have added jQuery to your page, as described above, you are ready to move on and learn more about jQuery in the coming chapters!