system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is the British pound (GBP) so strong against a lot of the worlds major currencies?

Even though the pound has weakened recently, it still out-values USD, EUR, AUD, etc. Why is this? What makes the GBP historically strong right up to current day strength?

Also - to expand - what makes a currency strong in the first place?
gpt
A lot of the value of a currency was simply made up. When money was still linked to precious metals the UK decided to make £1 worth 7.3g of gold while the US made $1 worth 1.5g. It didn't really matter that £1 was worth more than $1 as prices just reflected the amount of gold something was worth.

Since currencies are no-longer linked to precious metals the pound still has a higher numeric value because of that history, but proportionally it's lost more of its value than its earlier gold value so really it's become much weaker relatively (£1 used to be worth $4.8)

Now of course in general the numeric value doesn't matter, only whether the value goes up and down compared to other currencies - $1 is worth 100 YEN, but people have 100x more YEN so it's a bit like if the dollar were abolished and everyone just paid by the cent instead (you'd have a 1,000¢ bill instead of a $10 bill etc)