What are the big 3 in project management?

The "big 3" in project management, also known as the Triple Constraint or the Iron Triangle, are time, scope and cost. 

Time refers to the project schedule and deadline. It encompasses the duration of the project and the timeframe within which tasks must be completed. The scope represents the tasks required to fulfill the project's goals. It includes all the work that needs to be done to deliver the project's objectives. Cost also known as the project budget, this constraint covers the financial resources allocated to the project.

These three elements form the core constraints that project managers must balance to ensure project success.