Hi @Gurpreet Duhra, Welcome to the LeanIX Community.

Typically, a Predecessor is the Application that has been used before rolling out the Application that is currently in use (lifecycle = active). The successor is the Application that is planned to replace the current one. 

Imagine you’re currently using a CRM like Salesforce. The predecessor could have been a legacy, self-build CRM system that you used to have in your organization, while the successor would be the Application or Suite that you’re planning to introduce in order to move away from Salesforce.

Best,
Carsten