MQSeries products are queue managers and application enablers. They support the IBM Message Queue Interface (MQI) through which programs can put messages on a queue or get messages from a queue. With MQSeries, you can write applications that use MQSeries.
Applications that use MQSeries can share a queue through which they can pass messages to one another. See MQSeries Application Programming Guide for an introduction to MQSeries and for more information about programming with message queues.