What is a reference rate, and why does the ECB publish one every working day? Explain it simply

The European Central Bank publishes a euro reference rate for a set list of currencies each working day. For example, its euro-sterling reference rate was 0.8377 on 22 October (EUR/GBP report). It is one price, set at one time, which makes it a fixed point to compare against over months and years.

It is useful for checking a quote, for historical comparison and for reading the trend. It is not the price you would have received on a trade at another time of the day, because markets move through the day. The fixing is also published once and not revised, which makes it a useful record for checking a past date.

We would like the friendliest explanation in the community:

• How would you explain a reference rate to someone who only uses a phone app?
• When do you use an official rate, and when do you use a live price?
• Have you ever used the ECB series to check a broker's price?
• Which official source did you learn first, and how did it help?

How to trade EUR/USD is a good next read for a beginner.

Please keep replies friendly and practical. Posts that promise a direction or sell signals will be removed.