What is CSRF token and how will you add CSRF token in ajax?

A CSRF token is known as a unique, secret, unpredictable value that is generated by the server-side application. It is transmitted to the client in a way that is included in a subsequent HTTP request made by the client. CSRF stands for Cross-site request forgery.

You can add CSRF token in ajax as follows:

In between head, tag put <meta name="csrf-token" content="{{csrf_token()}}"> and in Ajax, we have to add the following code: 

$.ajaxSetup({
   headers: {
     'X-CSRF-TOKEN': $('meta[name="csrf-token"]').attr('content')
   }
});