what is services in angularjs? How to create and use it?

<!DOCTYPE html>
<html>

<head>
  <link rel="stylesheet" href="style.css">
  <script src="https://code.angularjs.org/1.3.14/angular.js"></script>
  <script>
   
    var baseURL = "http://localhost:9669/";
    var cartURL = "api/AddToCart_API/GetMyCarts/";
    var EmailID = "anil.singh581@gmail.com";
    var app = angular.module('cartOneAp', []);
    
    //This is services used to call the cast API.
    app.service("myCarts", function ($http) {
        this.getShopingCart = function (urls, EmailID) {
            return $http({
                method: 'GET',
                url: baseURL + urls + '/' + EmailID
            });
        };
    });

    //This is base controller used to call the getShopingCart details.
    app.controller('baseController', function ($scope, myCarts) {
       //This is default constant for shoping cart
       $scope.carts = null;
       $scope.email = EmailID;

       //Calling services by baseController
       myCarts.getShopingCart(cartURL, $scope.email).then(function (resp) {
           if (resp !== undefined && resp !== null) {
               if (resp.data !== undefined && resp.data !== null) {
                   $scope.carts = resp.data;
                   console.log($scope.carts);
               }
           }
       });
       //End : This is for shoping cart
    });
  </script>
</head>
<body ng-app="cartOneAp">
  <div>
    <div ng-controller="baseController">
      <ul>
          <a href="/Products/Cart/{{ProductID}}"><l>{{ProductName}}Click to Test</l></a>
      </ul>
    </div>
  </div>
</body>

</html>

// Code goes here

/* Styles go here */