As we know about payment gateways like paypal.In that PayPal Name-Value Pair (NVP) is a simple programmatic interface that allows the merchant, to access PayPal’s business functionality .
It is easy to integrate this to our application,just by sending a NVP String to the paypal API using valid credentials.
which we can get from our paypal account.
The concept is request and response.We are sending a request from our app with all the creditcard details and amount etc,The paypal will give the response according to the information we provided.
We can get the sample code from the following URL: