Bitcoin address changes?

[SgtSpike]

I'm really confused...

In my bitcoin.exe window, I have "Your Bitcoin Address:"

I use deepbit to mine, and so I sent some bitcoins from my pool account to this address.  It went through just fine, no issues.  Then I sent those bitcoins off to MtGox.  Just fine, no issues.

But now, the "Your Bitcoin Address:" has changed to something else!  So this is not a permanent address?  If not, how/when does it change, and how are vendors able to post their address in the marketplace if it is always changing?

[mewantsbitcoins]

Your client generates new address for every transaction. All your old addresses  are still valid and can be seen in Settings>Your Receiving Addresses. It is convenient because if you are a seller you can give every customer a new address and know if they paid or not

[SgtSpike]

I see, thanks for the explanation mewantsbitcoins!