1. **Problem:** What is the difference between **union** and **intersection** in sets? 2. **Union means “or”:** The union of two sets, written as $A \cup B$, means all elements that are in $A$, in $B$, or in both. 3. **Intersection means “and”:** The intersection of two sets, written as $A \cap B$, means only the elements that are in both sets. 4. **Formula examples:** $$A \cup B = \text{all elements in either set}$$ $$A \cap B = \text{only common elements}$$ 5. **Example:** If $A=\{1,2,3\}$ and $B=\{3,4,5\}$, then $$A \cup B = \{1,2,3,4,5\}$$ $$A \cap B = \{3\}$$ 6. **Easy way to remember:** - **Union** = combine everything. - **Intersection** = keep only what overlaps. 7. **Final answer:** **Union** means all elements from either set, while **intersection** means only the elements the sets share.