The Reactive Extensions (Rx) is a library for composing asynchronous and event-based programs using observable sequences and LINQ-style query operators. In traditional desktop or web-based applications, developers deal with asynchronous and even based programming from time to time. With the help of Rx, the observable interface notifies the subscribed observer interface whenever an event occurs. Since observable sequences are data streams, one can query those using standard LINQ query operators and filter, aggregate, compose and perform time based operations on multiple events.