How do you segment customer info to target (such as Industry) into your CRM?

It's quite grey area for me to distinguish what kind of industry or your customer is working at – For example, if they are working in a finance team but in school. I wasn't sure if they can be categorised as Finance or Education. We sometimes need to target groups depending on their interest, and one of example I was thinking about was their working industry. So in summary..

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1. How do you store their data about industry segment into your CRM?
2. Are there any other segments you find interesting or helpful?

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