We know that Integration Testing is a phase in software testing in which standalone modules are combined and tested as a single entity. During that phase, the interface and the communication between each one of those modules are tested. There are two popular approaches for Integration testing which is Top down Integration Testing and Bottom up Integration Testing.
In Hybrid Integration Testing, we exploit the advantages of Top-down and Bottom-up approaches. As the name suggests, we make use of both the Integration techniques.
It is viewed as three layers; viz - The Main Target Layer, a layer above the target layer and a layer below the target layer.
Testing is mainly focussed for the middle level target layer and is selected on the basis of system characteristics and the structure of the code.
Hybrid Integration testing can be adopted if the customer wants to work on a working version of the application as soon as possible aimed at producing a basic working system in the earlier stages of the development cycle.