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Any time you actually need to use the ordering property. For instance, if you have an ordered map with string keys, you can very efficiently find all the keys with a given prefix. With an unordered_map, you'd have to iterate through the entire data structure.

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Doing a string prefix search in an ordered map is actually not maximally efficient since you end up comparing the shared prefix over and over again during the binary search. You'd definitely don't want to be doing this with long prefixes.

Thanks for explaining the obvious, my self taught programming skills are unordered and my biggest obstacle is generally my not seeing what is right in front of me.

All of <algorithm> uses ordering operators as well. If you have a "regular" type with proper comparison and assignment operators, it works for everything, container keys, sorting, etc, etc.

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