Project Planning is the first phase out of a total of five phases within the Software Development Life Cycle (SDLC). 

The project planner’s role is the following:
Define the problem
Produce the project schedule
Confirm project feasibility
Staff the project
Launch the project

The aformentioned activities are generally considered to be Project Management tasks.

Critical Components of this phase include:
Business Benefits (Business Case)
System Scope Document
Context Diagram
Work Breakdown Schedules (WBS) – a list of all the individual tasks that are required to complete the project, usually composed in Microsoft Project Manager
PERT Chart (Project Evaluation and Review Technique) – Can be composed in Microsoft Project Manager

Economic Feasibility:
Cost/benefit analysis (Development costs, ongoing costs of operations)
Net Present Value (NPV)
Payback Period
Breakeven Point
Return on Investment