Checking several conditions at once
=AND(logical1, [logical2, ...]) =OR(logical1, [logical2, ...])
AND returns TRUE only when every condition is TRUE. OR returns TRUE when at least one is.
On their own they return TRUE or FALSE. Their real power shows up inside IF:
=IF(AND(B2>=4, C2>=2), "Yes", "No")
Cells that already hold TRUE/FALSE (like checkboxes) can be passed straight in: =OR(B2>5, C2).
NOT and XOR
NOT flips a single TRUE/FALSE. XOR means "one or the other, but not both": it's TRUE when an odd number of its conditions are TRUE.