Core Planning Process PMBOK.

Unfortunately, there's no way to really avoid this. You will need to understand how PMI defines the project planning process. In general, PMI defines the project planning process as the development and maintenance of the project plan. That's straightforward. However, it is the 11-step breakdown of core project planning and the inter-relationships among those 11 processes that may be "less than straightforward."

The PMBOK definition of project planning is accurate, complete, and logical. The confusing element is that in our real-life experiences, we simply have not thought about each of these steps in the same way as PMI. It is also possible that we, as project managers, simply execute these steps naturally (or in rare circumstances, perhaps this level of diligence is not always exercised during project planning).
describes how PMI defines the core project planning process, and the content in this table describes what depicts. Note that provides references back to where these processes can be found in the PMBOK. Pay particular attention to the PMBOK reference terminology.