Elastisity of Supply understand, difficulty, because, example

w1977

I understand elastisity of demand, but I'm having difficulty getting my mind around elastisity of supply.

When I think of E of demand, I think of neighboring gas stations. One raises it's price 5% and sales drop off 25% because of close substitutes.

What would be a good example of elastisity on the supply side? And, if there is elastisity of supply, does that necessarily mean that demand is inelastic?

Thank you,

- Robert