I work in finance and I still wonder why they can’t just decide to keep interest rates low and that inflation doesn’t need to be high.
@Horriblewoman - while "they" (ie the Bank of England) can directly change interest rates (by setting the rate it offers banks), there is no "they" who can just decide to reduce inflation.
If you're a manufacturer of bread and your raw ingredients are suddenly more expensive because less grain is coming out of Ukraine and other buyers are competing for the supply, and also fuel costs are higher so it costs more to bake bread, you either put up the price of bread so you can afford to run your business or go bust. Meanwhile, other sellers of goods and services are making the same sort of decisions, and prices rise - ie inflation.
The theory is that putting up interest rates, individuals are motivated to spend less (they are having to service higher debt or saving becomes more attractive), so with less demand, prices don't rise as quickly. (The bread manufacturer has to balance covering their costs with the point that the bread won't sell if people have less money to spend). Also, higher interest rates in the UK attract foreign currency investors, strengthening the pound and making it cheaper to import supplies like fuel and grain, so again the bread manufacturer can avoid making price hikes.