I particularly appreciate how you emphasized resource management - that's something many developers overlook until they run into performance issues with nested loops or heavy operations. Your examples are spot-on too. The array summation with a for loop and the user input validation with a while loop perfectly demonstrate when each type shines. I've found that the "known vs unknown iterations" rule you mentioned is probably the clearest way to decide between them. One thing I'd add from my experience is watching out for off-by-one errors, especially with array bounds. I can't count how many times I've seen i <= array.length instead of i < array.length cause issues. Also, for the while loop example, it's worth mentioning that you could use a do-while loop if you always want to execute the loop body at least once, like when you're guaranteed to need user input. The enhanced for loop (for-each) is another handy option when you're just iterating through collections without needing the index. It makes the code cleaner and eliminates those pesky index errors altogether