✔ What is a union, and how is it different from a structure?
✔ Declaring and defining a union using the union keyword
✔ Understanding memory allocation in unions
✔ Assigning values to union members
✔ Accessing and modifying union data
✔ Why only one member can hold a value at a time
✔ Memory allocation comparison
✔ Use cases for structures vs. unions
✔ Using pointers with unions
✔ Accessing union members using pointers
✔ Nesting a union inside a structure
✔ Practical applications of structure-union combinations