What are "hard quote" and "instant execution" in Forex?

External question — Personal Finance Stack Exchange Author: m2004 Original post: https://money.stackexchange.com/questions/64247 License: CC BY-SA 3.0 — https://creativecommons.org/licenses/by-sa/3.0/ Adaptation: HTML converted to plain text; contact email addresses removed. "Instant execution is a technology allowing traders to trade on so-called “hard” quotes." This is a piece of a text I just saw. What does these two terms mean?