Q-signals 
Q-signals are used as a short cut
for hams to send messages. For example if
I said
"QTH is
it saves a little wear and tear on
your morse code key.
But here's
another neat feature of Q-Signals. They're understood by everyone no
matter what language they speak.
An American ham that only speaks
English can communicate with a Ham that doesn't speak English. With
Q-signals an
entire contact can be made.
Q-signals can also be used to ask for information too...I would send 'QTH ?' I would be asking the other station for their location.
Here is a list of some of the more common Q-Signals and examples of how they are used during a radio contact (QSO).
QRM - your signal is being interfered with by another station
ex.. please repeat QRM from foreign station
QRN - your signal is being interfered with by static
ex. Your signal is strong but QRN from storm nearby
QRO - I am transmitting using High Power
ex. QRO here 1000 watts
QRP - I am transmitting using Low Power
ex. I am QRP only 1 watt
QRT - I am done transmitting and will not answer any stations calling me.
ex. good night, K9WIS is QRT
QRV - I am ready to receive your message
ex. QRV your emergency message.
QRX - Please wait, I'm not ready to receive your message
ex. QRX I need to find a pencil
QRZ ? - Who is calling me?
ex. QRZ ? the station from Antarctica?
QSB - your signal is fading in and out
ex. I can copy you but QSB
QSL - I confirm your message (I got it ok)
ex. QSL your address I will send a card
QSO - radio contact
ex. I had a nice QSO with W1AW
QSY - I am changing my frequency
ex. I will QSY up 1 KHz
QTH - I am located at ....
ex. My QTH is Waterford, Wi.