What is resonance or resonant frequencies?

It seems my quetion got deleted by yahoo. quote In physics, resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies, known as the system's resonance frequencies (or resonant frequencies). At these frequencies, even small periodic driving forces can produce large... show more It seems my quetion got deleted by yahoo.

quote
In physics, resonance is the tendency of a system to oscillate at maximum amplitude at certain frequencies, known as the system's resonance frequencies (or resonant frequencies). At these frequencies, even small periodic driving forces can produce large amplitude vibrations, because the system stores vibrational energy.

Or +++ When you play a tune on one, then another instrument with the same acoustic resonance will pick up that tune, it will visibly vibrate
______________________________________...

I'm having hard time understanding the above it is from wikipedia.Also how does electromagnetic induction work?

And is electromagnetic induction the same has megentic induction .

++++
Quote
creation of electric or magnetic forces: the process by which electric or magnetic forces are created in a circuit by being in proximity to an electric or magnetic field or a varying current without physical contact
__________________________
Also can some one explain the above better.I know a electric curent makes a magnetic force in wire.Any current you got a magnetic force.
10 answers 10