The Tobin rate is the idea of economist James Tobin, Nobel Prize in Economics of 1981, which consisted in taxing financial transactions of foreign exchange.
That this economist proposed the establishment of this tax has its raison d’etre. It was in the early 70s. Shortly before, US President Richard Nixon had ended the fixed parity between the dollar and gold (Established in Bretton Woods – 1944), propitiating speculation with fluctuations in The types of changes.
This is the feat of George Soros in September 1992, known as Black Wednesday . Day on which he decided to earn the wage by converting 10,000 million pounds into German marks to resell them once the pound had depreciated. Because by losing value a pound, Soros was able to resell the frames, obtaining more pounds in return.
The devaluation of the pound occurred as a result of the Soros operation, which caused more investors to do the same, and the economic weakness that England was going through. So the Bank of England had no choice but to depreciate its currency instead of playing with interest rates (increasing them to make the pound more attractive)
In conclusion, Tobin dealt with his rate of impeding the gain of money simply by playing with the exchange of one currency to another.
What does the latter mean? For your explanation, what better than to resort to a real case. Real at the same time as extreme, but that reflects very well what Tobin wanted to avoid at the time with his rate.