An RFQ is an electronic message sent by one bank to another bank to start a trade.

An RFQ can be sent to a bank just to see the pricing of a financial instrument, there is no obligation to trade.

RFQ is a concept in electronic interbank trading, when the banks do not trade via an exchange but directly with each other. 

An RFQ is the opening price of a financial instrument on an exchange.

An RFQ is when broker demands a designated sponsor to give a price for Bid/Offer.

An RFQ would be connected to a pricer, so the bank can issue quotes automatically. 

An RFQ would normally be followed by an offer to buy/sell a financial instrument.