Why is deflation bad?

Question:

Although I studied economics at an undergraduate level and have spent almost a decade working for financial advisers, I've never understood the idea of target inflation ranges or why some countries are described as 'struggling with low inflation'. Is inflation a measure of the rising cost of living? Or is it a measure of the declining value of money? Perhaps it's both i.e. some sort of inverse relationship? Why do economies target an inflation range? I can't understand why we would want the cost of living to rise or want the value of our money to fall. If a country has low inflation, does that mean the cost of living is increasing at a low rate? And wouldn't that be a good thing for the population? Taking that a step further, wouldn't it be even better if the cost of living was declining over time (I believe that's called deflation)? Why is deflation a bad thing? Thanks in advance!

Answer:

If prices are not rising at all over time or even falling, it would act as an disincentive for firms to produce goods for the market. For durables, if people expect prices to fall, they will wait. Since most financial contracts are denominated in dollars, deflation would hurt borrowers and help creditors (if you borrow $100 from me and pay me back a year from now, then even with no interest earned, say, I would get more than $100 in real, purchasing power terms because prices have fallen.)