What is "strict meter"?

Daniella writes:
"I was wondering if there are any specific instances where Poe uses a foot like a dactyl or a trochee to place certain emphasis on a word or phrase, or does he usually stick to extremely strict meter with no exceptions?"

Any poet who stuck to the exact same metrical scheme for more than four or five lines at a time would risk sounding too monotonous, like a metronome (remember the insidious "tick-tock" of the metronome keeping perfect time during your piano lessons?). Every singer knows that you can have a basic beat going in the background, but that your performance in the foreground had better come up with some variations. That might be another way to think about meter: it's the "background beat" to a musical performance that is going to have to make a few deviations from being exactly "on" if it hopes to be listenable.

Just as with a poem, the moments where the singer draws a note out---aaaaah--or lumps a bunch of words together quickly, or otherwise makes something interesting happen in the melody line, call our attention.