upper bound, lower bound
algorithm, complexity-theory, time-complexity
Solution
Proving an upper bound means you have proven that the algorithm will use no more than some limit on a resource.
Proving a lower bound means you have proven that the algorithm will use no less than some limit on a resource.
"Resource" in this context could be time, memory, bandwidth, or something else.
Problem
What does it mean to prove an upper bound or lower bound to an algorithm?